A high-entropy metal-organic gel membrane electrode, preparation thereof and application thereof in bromide ion separation

Abstract

This invention belongs to the field of new materials technology, specifically relating to a high-entropy metal-organic gel membrane electrode, its preparation, and its application in bromide ion separation. The preparation method of the high-entropy metal-organic gel membrane electrode includes the following steps: (1) dissolving a soluble metal salt in anhydrous ethanol at an equimolar ratio to prepare a metal salt solution; (2) dissolving an organic ligand in anhydrous ethanol to prepare an organic ligand solution; (3) immersing the pretreated carbon felt in the metal salt solution prepared in step (1) for 12–24 h, and then placing it in the organic ligand solution prepared in step (2) for 0.5–3 h to obtain the high-entropy metal-organic gel membrane electrode. This material has a hierarchical porous structure and abundant amorphous high-energy adsorption sites. Under the synergistic effect of high-entropy multi-metal centers (Fe, Cu, Al, Zn, Zr), it achieves the adsorption of Br- ions. ‑ Highly selective capture.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a high-entropy metal-organic gel membrane electrode, its preparation, and its application in bromide ion separation. Background Technology

[0002] Bromine, as a high-value-added element, is widely used in pharmaceuticals, flame retardants, and other fields. - Widely found in seawater, underground brine, salt lakes, and wastewater, bromine easily causes pollution and equipment corrosion. With increasing global demand, developing green and efficient bromine extraction technologies is crucial. While mainstream ion exchange and adsorption methods are effective, they suffer from limitations such as secondary pollution and low capacity. Electro-controlled ion exchange technology combines the advantages of electrochemistry and ion exchange, achieving reversible ion adsorption and release through potential regulation, offering both environmental friendliness and high efficiency. The core performance of this technology lies in the structural characteristics of the electroactive ion exchange membrane, such as electroactivity, pore structure, interlayer spacing, and specific recognition sites. Therefore, designing and constructing ESIX membrane electrodes with directional structural features is essential for achieving bromine extraction. - The key to selective extraction.

[0003] In recent years, metal-organic frameworks (MOFs), metal-organic gels (MOGs), and their derivatives (MOF(D)) have shown promising applications in areas such as metal ion adsorption. MOFs, assembled from metal clusters and organic ligands, possess regular pore structures and high specific surface areas, demonstrating significant potential in multiple fields. Using MOFs as precursors or directly constructing novel porous materials holds promise for achieving excellent liquid-phase adsorption performance. For example, Zhang et al. designed a boron-containing two-dimensional MOF, utilizing the synergistic effect of boron and metal sites to enhance the specific adsorption of fluorine. Despite the advantages of MOFs in terms of structure and specific surface area, their demanding synthesis conditions and complex molding processes still limit their practical applications.

[0004] Metal-organic gels (MOGs) are a class of three-dimensional network soft materials formed by the self-assembly of metal ions / clusters and organic ligands through coordination interactions. They combine the advantages of metal-organic frameworks (MOFs) such as porosity, high specific surface area, tunable structure, and abundant host-guest interaction sites, while also possessing the morphological flexibility and mild synthesis conditions unique to gels. Therefore, they have shown application potential in multiple fields. However, traditional MOGs as adsorbent materials still face problems such as single active sites, insufficient chemical stability, and limited functional tunability, which restrict their application in complex practical scenarios.

[0005] High-entropy materials refer to single-crystal solid solutions composed of five or more elements in equimolar or near-equimolar proportions. Their high configurational entropy reflects the high degree of disorder in the atomic arrangement within the crystal, endowing the material with four core effects, thus exhibiting excellent structural stability, ionic conductivity, mechanical strength, and catalytic activity, making them promising for applications in the field of electrochemistry. These properties make high-entropy materials suitable for use in various battery components such as electrodes and electrolytes. For example, the application of high-entropy strategies to Prussian blue analogues as cathode materials for lithium-sulfur batteries has attracted widespread attention.

[0006] This invention introduces a high-entropy strategy into metal-organic gels to construct high-entropy metal-organic gel membrane electrodes, thereby overcoming the shortcomings of traditional MOF materials in terms of structure and performance. Summary of the Invention

[0007] In view of the problems and shortcomings of the existing technology, the present invention aims to provide a high-entropy metal-organic gel membrane electrode, its preparation and its application in bromide ion separation.

[0008] To achieve the objectives of this invention, the technical solution adopted is as follows: The first aspect of this invention provides a method for preparing a high-entropy metal-organic gel membrane electrode, comprising the following steps: (1) Dissolve soluble metal salts in anhydrous ethanol in an equimolar ratio to prepare a metal salt solution; wherein the metal is one of five of the following: Cu, Al, Fe, Zr, Zn, Mn, Co, Ni, Cd, and Cr; (2) Dissolve the organic ligand in anhydrous ethanol to prepare an organic ligand solution; (3) Soak the pretreated carbon felt in the metal salt solution prepared in step (1) for 12-24 h, and then soak it in the organic ligand solution prepared in step (2) for 0.5-3 h to obtain a high-entropy metal-organic gel membrane electrode. Soaking and standing in this step are carried out at room temperature without additional heating.

[0009] Preferably, the metal in step (1) is Cu, Al, Fe, Zr, or Zn.

[0010] Preferably, the soluble metal salt in step (1) is a nitrate of the metal.

[0011] Preferably, the total concentration of metal ions in the soluble metal salt solution in step (1) is 0.5 to 2.5 mol / mL.

[0012] More preferably, the total concentration of metal ions in the soluble metal salt solution in step (1) is 2.5 mol / mL.

[0013] Preferably, the concentration of the organic ligand in step (2) is 0.05 to 0.25 mol / mL.

[0014] More preferably, the concentration of the organic ligand in step (2) is 0.25 mol / mL.

[0015] Preferably, the organic ligand is one of pyromellitic acid, 4,4',4''-triphenylamine tricarboxylate, 2,4,6-tris[(p-carboxyphenyl)amino]-1,3,5-triazine, 1,4-naphthalenedicarboxylic acid, tetrafluoroterephthalic acid, 2-aminoterephthalic acid, 2-(4-(1-imidazolyl)-phenyl)-imidazolium, and 2-(4-pyridyl)-imidazolium.

[0016] More preferably, the organic ligand is pyromellitic acid.

[0017] A second aspect of the present invention provides a high-entropy metal-organic gel membrane electrode prepared using the preparation method described in the first aspect.

[0018] The third aspect of this invention provides an application of the high-entropy metal-organic gel membrane electrode described in the second aspect in bromide ion separation.

[0019] The fourth aspect of the present invention provides a method for separating bromide ions by electro-controlled ion exchange, wherein the high-entropy metal-organic gel membrane electrode described in the second aspect is used as the working electrode and the carbon plate electrode is used as the counter electrode to extract bromide ions from a bromide-containing aqueous solution.

[0020] Preferably, the concentration of the bromine-containing aqueous solution is 200–1000 mg / L, and the electrode potential is 0.2–0.6 V.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention employs an in-situ growth strategy to construct a high-entropy metal-organic gel (FeCuZrZnAl-MOG) membrane adsorption material on a carbon felt substrate. This material possesses a hierarchical porous structure and abundant amorphous high-energy adsorption sites. Through the synergistic effect of the high-entropy multi-metal centers (Fe, Cu, Al, Zn, Zr), it achieves the adsorption of Br₂. - Highly selective capture.

[0022] (2) The lattice distortion induced by the high entropy effect pins atoms through the "slow diffusion effect," enhancing structural stability while synergistically improving the density of active sites and ion transport efficiency. Among them, Fe and Cu, as redox active centers and electronic control sites respectively, directly participate in Br₂. - Coordination adsorption; Al and Zn act as "sacrificial templates" to form abundant meso-macropore channels; Zr enhances the structural stability of the material.

[0023] (3) In the optimized “One-Two” electro-controlled ion exchange (ESIX) working system, this adsorbent effectively overcomes the problem of insufficient utilization of active sites in the traditional mode, at 1000 mg / L Br - Br in solution - The adsorption capacity can reach 123.55 mg·g -1 This invention provides new materials and methods for the efficient and selective recovery of bromine resources from brine. Attached Figure Description

[0024] Figure 1 A schematic diagram of the fabrication of the FeCuZrZnAl-MOG membrane electrode; Figure 2 A comparative graph showing the effect of different organic ligand concentrations on bromine adsorption capacity; Figure 3 Comparison of the appearance stability of five groups of FeCuZrZnAl-MOG prepared under different entropy change conditions; Figure 4 Five groups of FeCuZrZnAl-MOG prepared under different entropy change conditions were subjected to 0.5 M Br. - (a) Cyclic voltammetry curve in solution; (b) 50 mV·s -1 (c) Electrochemical stability comparison at different scan rates; (d) Adsorption capacity plot; (e) Dependence of configuration entropy on the number of elements. Figure 5 SEM images and EDS images of FeCuZrZnAl-MOG at different magnifications; Figure 6 (a) Tem image of FeCuZrZnAl-MOG at a 500 nm scale; (b) Tem image at a 100 nm scale; (c) Schematic diagram of the flower cluster structure; (d) Tem image magnified at a 5 nm scale highlighting the material's network structure; (e) Tem image highlighting the material's porous structure at a 10 nm scale and a simulated thermal view; (f) Schematic diagram of the porous network structure; (g) Schematic Tem image highlighting the material's amorphous structure at a 5 nm scale and a simulated thermal view; (h) Tem image with SAED pattern; (i) Schematic diagram of the amorphous structure; Figure 7 For FeCuZrZnAl-MOG in ESIX and IX systems at 1000 mg / L Br - In solution: (a) Adsorption capacity curve; (b) Adsorption capacity comparison graph; (c) Blank control experiment of FeCuZrZnAl-MOG; (d) Adsorption capacity of FeCuZrZnAl-MOG on Br in One-One and One-Two systems. - Adsorption capacity curve; Figure 8 The graph shows the zeta potential test results for FeCuZrZnAl-MOG. Figure 9 For FeCuZrZnAl-MOG at different (a) potentials; (b) loading amounts; (c) initial concentrations of Br - (d) Adsorption capacity curve; (e) Pseudo-first-order kinetics; (f) Pseudo-second-order kinetics curve; (c) Piecewise fitting curve of internal diffusion model; Figure 10 The adsorption kinetics curves of FeCuZrZnAl-MOG at different temperatures are shown in (a) and (b) the thermodynamic fitting curves are shown in (b). Figure 11 (a) Selectivity of FeCuZrZnAl-MOG; (b) Cyclic voltammetry curves in 0.5 M KBr, KF, KCl and K2SO4 solutions; (c) Desorption capacity curves at different potentials in 0.1 M NaNO3 solution; (d) Cyclic stability; Figure 12 (a) XRD pattern of FeCuZrZnAl-MOG; (b) Fourier transform infrared spectrum; (c) Raman spectrum; (d) TG-DTG spectrum; Figure 13 For FeCuZrZnAl-MOG adsorption of Br - XPS spectra before and after: (a) full spectrum, (b) Br 3d, (c) C 1s, (d) O 1s, (e) Fe 2p, (f) Cu 2P, (g) Zn 2P, (h) Zr 3d, (i) Al 2P peak spectrum. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] (I) Effect of different organic ligand concentrations on the performance of high-entropy organometallic organogel membrane electrode materials Example 1: Preparation of high-entropy metal-organic gel film electrode material A method for preparing a high-entropy metal-organic gel membrane electrode, the preparation process is as follows: Figure 1 As shown, the specific steps are as follows: (1) Weigh 2.0133 g of copper nitrate trihydrate, 3.1261 g of aluminum nitrate nonahydrate, 3.3667 g of ferric nitrate nonahydrate, 3.5775 g of zirconium nitrate pentahydrate, and 2.4790 g of zinc nitrate hexahydrate and add them to 16.67 mL of anhydrous ethanol. Stir thoroughly until dissolved to obtain a mixed metal salt solution with a total metal ion concentration of 2.5 mol / L. (2) Weigh 1.7512 g of pyromellitic acid and add it to 33.34 mL of anhydrous ethanol. Stir thoroughly until dissolved to prepare an organic ligand solution with a concentration of 0.05 mol / L. (3) The 3.5 cm × 5.5 cm carbon felt conductive substrate was soaked in 0.5 M H2SO4 solution and anhydrous ethanol for 2 h in sequence, then rinsed with anhydrous ethanol and dried to obtain the pretreated carbon felt; the pretreated carbon felt was soaked in the metal salt solution prepared in step (1) for 24 h to allow the metal ions to fully penetrate into the carbon felt as a signal source for gel formation; then it was placed in the organic ligand solution prepared in step (2) and left to stand for 3 h to allow the metal ions in the carbon felt to fully combine with the organic ligand solution. At this time, pyromellitic acid served as the carbon source for gel formation. The metal ions and organic ligands reacted fully in the carbon felt system to form a gel network, which was then directly grown onto the carbon felt support to obtain the high-entropy metal-organic gel film electrode material (FeCuZrZnAl-MOG).

[0028] In the preparation of metal-organic gel membrane electrodes, it is necessary to calculate the mass of the loaded active material. The mass of the loaded active material is determined by the mass difference method: first, accurately weigh the mass of the dried empty carbon felt, then place the loaded gel carbon felt in an oven to dry to constant weight and weigh it again. The difference between the two is the mass of the loaded active material for each carbon felt electrode, which is the mass of the electroactive membrane material on the conductive substrate, facilitating the calculation of the bromide ion adsorption capacity below. In Example 1, the mass of the loaded active material was 0.309 g.

[0029] Example 2 A method for preparing a high-entropy metal-organic gel membrane electrode is provided. The preparation process is basically the same as that in Example 1, except that the concentration of the organic ligand solution in step (2) is 0.1 mol / L. The mass of the active material loaded in Example 2 is 0.310 g.

[0030] Example 3 A method for preparing a high-entropy metal-organic gel membrane electrode is basically the same as that in Example 1, except that the concentration of the organic ligand solution in step (2) is 0.15 mol / L. The mass of the active material loaded in Example 3 is 0.313 g.

[0031] Example 4 A method for preparing a high-entropy metal-organic gel membrane electrode is basically the same as that in Example 1, except that the concentration of the organic ligand solution in step (2) is 0.2 mol / L. The mass of the active material loaded in Example 4 is 0.315 g.

[0032] Example 5 A method for preparing a high-entropy metal-organic gel membrane electrode is basically the same as that in Example 1, except that the concentration of the organic ligand solution in step (2) is 0.25 mol / L, and the material obtained is denoted as P-MOG. The mass of the active material loaded in Example 5 is 0.318 g.

[0033] Performance testing: The effect of high-entropy metal-organic gel membrane electrode materials prepared in Examples 1 to 5 on Br - The adsorption capacity was determined using the following method: FeCuZrZnAl-MOG prepared in Examples 1-5 was used as the working electrode, and a carbon plate electrode as the counter electrode. At an electrode potential of 0.3 V, adsorption capacity was measured against a sample containing 1000 mg·L⁻¹ of FeCuZrZnAl-MOG. -1 Br - Br in aqueous solution - The electro-extraction performance was tested. The bromide ion adsorption capacity Q (mg·g) of the metal-organic gel membrane electrode was calculated using Equation 1. -1 ): (1); In the formula, C0 (mg·L) -1 ) and C e (mg·L) -1 ) respectively correspond to Br in the solution - The initial concentration and the final equilibrium concentration are given by V (L), which is the volume of the solution, and m (g), which is the mass of the electroactive film material on the conductive substrate.

[0034] Examples 1-5: High-entropy metal-organic gel membrane electrode materials for Br - The adsorption capacity test results are as follows Figure 2 As shown, Br - The adsorption capacity increased with increasing organic ligand concentration (0.05M–0.25M), reaching a maximum of 123.55 mg·g⁻¹ at a concentration of 0.25M. Considering both adsorption performance and ligand solubility, 0.25M was determined to be the optimal concentration.

[0035] (II) The Influence of Different Types of Entropy Change Metals on Organic Gel Membrane Electrodes Comparative Example 1 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 16.835 g of ferric nitrate nonahydrate is weighed and added to 16.67 mL of anhydrous ethanol to prepare a metal salt solution with a total metal ion concentration of 2.5 mol / L. The material prepared is denoted as M-MOG.

[0036] Comparative Example 2 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 5.03 g of copper nitrate trihydrate and 8.42 g of ferric nitrate nonahydrate are weighed and added to 16.67 mL of anhydrous ethanol and mixed to obtain a mixed metal salt solution with a total metal ion concentration of 2.5 mol / L. The material prepared is called B-MOG.

[0037] Comparative Example 3 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 3.36 g of copper nitrate trihydrate, 5.21 g of aluminum nitrate nonahydrate, and 5.61 g of ferric nitrate nonahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 2.5 mol / L. The material prepared is called T-MOG.

[0038] Comparative Example 4 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 2.52 g of copper nitrate trihydrate, 3.91 g of aluminum nitrate nonahydrate, 4.21 g of ferric nitrate nonahydrate and 4.47 g of zirconium nitrate pentahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 2.5 mol / L. The material prepared is called Te-MOG.

[0039] Performance testing 1. Stability test: The membrane electrode materials prepared in Example 5 and Comparative Examples 1 to 4 were placed in air, and the morphological changes of the materials over time were observed. The stability test results of the five metal-organic gel membrane electrode materials with different entropy changes are as follows: Figure 3 As shown, when the metal type is singular, the material's appearance deteriorates significantly over time; as the number of metal types increases (entropy increase effect), the material's appearance is maintained relatively well, its stability is significantly enhanced, and its decay rate is significantly slowed down.

[0040] 2. Electrochemical performance testing: The membrane electrode materials prepared in Example 5 and Comparative Examples 1 to 4 were used as the working electrodes, a carbon plate as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a 0.5 M Br₂ electrolyte. - Solution, at 5 mV·s -1 Cyclic voltammetry curves were obtained by scanning at a rate of -0.8 to 0.8 V.

[0041] At a scan rate of 50 mV·s⁻¹, cyclic voltammetry (CV) scans were performed on the working electrode for 2000 cycles. The integral area of ​​the CV curve for each cycle was calculated using Origin software. Subsequently, a data point was selected every 100 cycles as a representative data point. All data points were normalized, and finally, the electrochemical stability curve was plotted.

[0042] Cyclic voltammetry curves as shown Figure 4 As shown in (a), the curve shows a pair of redox peaks at approximately 0.6 V and 0.3 V, corresponding to the valence state transitions of Fe³⁺ / Fe²⁺ and Cu²⁺ / Cu⁺ under the action of Br⁻. The M-MOG prepared in Comparative Example 1 only shows a weak Fe³⁺ / Fe²⁺ peak, with a small electroactive area, poor stability, and low adsorption capacity. With the increase of metal species, the CV area of ​​B-MOG prepared in Comparative Example 2 and T-MOG prepared in Comparative Example 3 increases significantly, and the electrochemical stability improves accordingly. Figure 4 (b) indicates that a moderate entropy increase optimizes the surface activity of the material. Although the CV area of ​​Te-MOG prepared in Comparative Example 4 and P-MOG prepared in Example 1 decreased due to the reduced Fe³⁺ / Cu²⁺ concentration, both exhibited further improved electrochemical stability under higher entropy changes, with P-MOG showing an electrochemical stability improvement of more than 60% compared to M-MOG. This is mainly attributed to the severe lattice distortion induced by the high-entropy system, which pins atoms to low-energy sites and effectively hinders dislocation movement through slow diffusion effects and high lattice frictional stress, thereby synergistically enhancing the strength and stability of the material.

[0043] 3. Adsorption capacity test: The adsorption capacity testing method is the same as above. The adsorption capacity results of five metal-organic gel membrane electrode materials with different entropy changes are as follows: Figure 4 As shown in (d), it can be seen from the figure that the adsorption performance of Br⁻ increases with the increase of metal types (entropy increase effect).

[0044] 4. Configurational entropy test: The configurational entropy (ΔS) of the five organometallic gels was calculated using Equation 2: (2); Where R is the molar gas constant, C i It is the mole fraction of the i-th metallic element.

[0045] The configurational entropy of five metal-organic gel membrane electrode materials with different entropy changes are as follows: Figure 4 As shown in d, ΔS increases monotonically with the increase of metal type, which is consistent with the basic characteristics of high-entropy materials. The moderate increase of entropy introduces controllable "beneficial disorder" at the atomic scale, which becomes a key factor in improving the overall performance of materials, successfully integrating high capacity, fast dynamics and long-term stability, which are usually difficult to achieve simultaneously.

[0046] (III) Effects of different total metal concentrations on high-entropy organometallic gel membrane electrode materials Example 6 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 0.403 g of copper nitrate trihydrate, 0.625 g of aluminum nitrate nonahydrate, 0.673 g of ferric nitrate nonahydrate, 0.716 g of zirconium nitrate pentahydrate, and 0.496 g of zinc nitrate hexahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 0.5 mol / L. The material prepared is called HEMOG-1. The mass of the active material loaded in Example 6 is 0.111 g.

[0047] Example 7 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 0.805 g of copper nitrate trihydrate, 1.251 g of aluminum nitrate nonahydrate, 1.347 g of ferric nitrate nonahydrate, 1.431 g of zirconium nitrate pentahydrate, and 0.992 g of zinc nitrate hexahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 1.0 mol / L. The material prepared is called HEMOG-2. The mass of the active material loaded in Example 7 is 0.172 g.

[0048] Example 8 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 1.21 g of copper nitrate trihydrate, 1.88 g of aluminum nitrate nonahydrate, 2.02 g of ferric nitrate nonahydrate, 2.15 g of zirconium nitrate pentahydrate, and 1.49 g of zinc nitrate hexahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 1.5 mol / L. The material prepared is called HEMOG-3. The mass of the active material loaded in Example 8 is 0.220 g.

[0049] Example 9 A method for preparing a metal-organic gel membrane electrode is basically the same as that in Example 5, except that: in step (1), 1.61 g of copper nitrate trihydrate, 2.50 g of aluminum nitrate nonahydrate, 2.69 g of ferric nitrate nonahydrate, 2.86 g of zirconium nitrate pentahydrate, and 1.98 g of zinc nitrate hexahydrate are weighed and added to 16.67 mL of anhydrous ethanol to obtain a mixed metal salt solution with a total metal ion concentration of 2.0 mol / L. The material prepared is called HEMOG-4. The mass of the active material loaded in Example 9 is 0.280 g.

[0050] Adsorption performance test: At 0.3V, the adsorption kinetics curves of FeCuZrZnAl-MOG membrane electrodes with different gel loadings prepared in Examples 6-9 and Example 5 were tested. HEMOG-5 is the FeCuZrZnAl-MOG membrane electrode prepared in Example 5. The results are as follows: Figure 9 As shown in (b), with the increase of gel loading, the equilibrium adsorption capacity and adsorption rate also increase. HEMOG-5 has the highest equilibrium adsorption capacity and the fastest adsorption rate, indicating that its loading provides sufficient active sites while maintaining a favorable environment for Br. - Open-channel structure for mass transfer.

[0051] Example 10 Morphology characterization of FeCuZrZnAl-MOG film electrode material The morphology of the FeCuZrZnAl-MOG film electrode material prepared in Example 5 was characterized, and the specific tests are as follows: 1. SEM-EDS test Scanning electron microscopy (SEM) characterization results are as follows: Figure 5 As shown, the high-entropy metal-organic gel (FeCuZrZnAl-MOG) prepared by the in-situ growth strategy is uniformly distributed inside the carbon felt substrate. Figure 5 (a, 5b) indicates that the material is well bonded to the conductive substrate, which is beneficial for subsequent Br... - Contact and adsorption. The surface of the FeCuZrZnAl-MOG film electrode material exhibits a continuous, dense, and smooth morphology. Figure 5 c), exhibiting excellent film-forming properties; its interior is a uniformly distributed, interconnected three-dimensional porous network structure ( Figure 5 d) The porosity reaches 96%, confirming that the material has excellent mass transport capabilities and accessibility of active sites. Figure 5The EDS analyses in the two columns on the right confirm that multiple metal elements are uniformly distributed in the material, ensuring the uniformity of active sites and laying the compositional foundation for the material to achieve stable electrochemical adsorption performance. The FeCuZrZnAl-MOG membrane material is macroscopically firmly bonded to the carbon felt, and microscopically possesses both a dense surface and a porous internal structure; the dense surface layer enhances interfacial stability, while the internal interconnected porous network provides efficient ion transport channels.

[0052] 2. TEM test Transmission electron microscopy (TEM) characterization results are as follows Figure 6 As shown, the multi-level structural characteristics of the FeCuZrZnAl-MOG film material are revealed, and the material is composed of dense "flower cluster" units. Figure 6 a~6c), significantly increasing the specific surface area. The well-developed internal porous network structure has pore sizes concentrated in the range of several nanometers (a~6c). Figure 6 d~6f), and Br - The matching hydration diameter facilitates selective trapping and the construction of low-resistance ion diffusion channels. Neither the SAED image nor the high-resolution image shows clear lattice or diffraction fringes. Figure 6 (g~6h) confirms that the material is generally amorphous. This amorphous structure contains a large number of unsaturated bonds and defects, exposing a high density of active sites ( Figure 6 i). Figure 6 The g-thermal simulation diagram further shows that its surface energy distribution is uneven, with a large number of high-energy sites, which are Br - It provides adsorption sites with high binding affinity. Among these, the nanopores provide size sieving and rapid mass transfer pathways, while the high-energy adsorption sites generated by the amorphous structure enable the material to possess high Br⁻ content. - The fundamental reason for adsorption capacity.

[0053] Example 11 Br of FeCuZrZnAl-MOG film electrode material - Adsorption performance I. Controlled Experiment 1. Experimental Methods (1) The FeCuZrZnAl-MOG membrane electrode material was tested in ion exchange (IX) system and electrochemically assisted ion exchange (ESIX) system at 1000 mg / L Br. - Adsorption capacity in solution: Using the FeCuZrZnAl-MOG membrane electrode prepared in Example 5 as the working electrode, with a carbon plate on each side as the counter electrode and an Ag / AgCl electrode as the reference electrode, the adsorption capacity for Br was compared under conditions of 0.3 V applied and no voltage applied. - Adsorption performance.

[0054] (2) In the electrically controlled ion system, the FeCuZrZnAl-MOG membrane electrode material prepared in Example 5 and the original carbon felt (blank control) were used as working electrodes, respectively. A carbon plate was placed on each side as a counter electrode, and the Ag / AgCl electrode was used as a reference electrode. Under the condition of applying a voltage of 0.3V, the concentration of Br at 1000 mg / L was tested. - Adsorption capacity in solution.

[0055] (3) In the electro-controlled ion exchange system, the first group used a FeCuZrZnAl-MOG membrane electrode (working electrode) and a single carbon plate (counter electrode), denoted as the "One-One" system; the second group placed the FeCuZrZnAl-MOG membrane electrode in the middle as the working electrode, and placed a carbon plate on each side as the counter electrode, forming a "One-Two" system. Other conditions were the same as above, and the test was conducted at 1000 mg / L Br - Adsorption capacity in solution.

[0056] 2. Experimental Results (1) FeCuZrZnAl-MOG membrane electrode materials in ion exchange (IX) system and electrochemically assisted ion exchange (ESIX) system at 1000 mg / L Br - The adsorption capacity curve in the solution is as follows: Figure 7 As shown in (a), the equilibrium adsorption capacity comparison diagram is as follows: Figure 7 As shown in (b). Figure 8 The zeta potential test results showed that its potential was +9.30 mV at pH=7, which, although positively charged, was beneficial for driving Br. - Electrostatic adsorption occurs, but this potential value is at the edge of the stability critical region, and the adsorption driving force is limited. In the electrochemically assisted ion exchange (ESIX) system, FeCuZrZnAl-MOG exhibits electrostatic adsorption of Br. - Both the adsorption rate and equilibrium capacity were significantly higher than those of the IX system. Figure 7 (b) indicates that its adsorption process mainly relies on electrochemical assistance. Applying a potential may modulate the surface charge state and induce Fe 3+ / Cu 2+ Valence state transitions provide additional driving force for adsorption, thereby accelerating mass transfer and increasing the adsorption limit.

[0057] (2) The adsorption capacity curves of FeCuZrZnAl-MOG membrane electrode material and the original carbon felt (blank control) are as follows: Figure 7 As shown in (c), the control experiment further verified the intrinsic activity of FeCuZrZnAl-MOG. The adsorption capacity of the electrode loaded with FeCuZrZnAl-MOG (CF+HEMOG) was much higher than that of the bare carbon felt (CF), which eliminated the interference of the substrate and confirmed that the high adsorption performance was entirely due to the HEMOG material.

[0058] (3) The adsorption capacity curves of the “One-One” system and the “One-Two” system are as follows: Figure 7 As shown in (d), the adsorption capacity of the One-Two system is more than twice that of the One-One system. This is because the contact between the gel and Br⁻ is limited in the traditional one-chamber structure, while the two-chamber system avoids this problem, allowing the reaction to proceed more fully. In summary, combining the high-entropy characteristics of FeCuZrZnAl-MOG with electrochemical regulation produces a synergistic effect of "1+1>2", achieving a significant improvement in bromine adsorption performance.

[0059] II. Single-factor experiment 1. Br at different potentials - Adsorption capacity curve To determine the electrochemically assisted adsorption of Br by FeCuZrZnAl-MOG - The optimal potential was determined using the FeCuZrZnAl-MOG membrane electrode prepared in Example 5 as the working electrode, with a carbon plate placed on each side as the counter electrode. Tests were conducted within the range of 0.2–0.6 V, and the results were performed at different electrode potentials at 1000 mg / L Br. - Adsorption kinetics curves in solution.

[0060] To determine the electrochemically assisted adsorption of Br by FeCuZrZnAl-MOG - The optimal potential was tested within the range of 0.2–0.6V. The results showed ( Figure 9 a) The adsorption capacity reaches its peak at 0.3V, which is related to the Fe in CV. 3+ / Cu 2+ The reduction peaks were consistent with those of the sample, indicating that the change in valence state could effectively drive adsorption. Therefore, 0.3V was selected for subsequent experiments.

[0061] 2. Br at different initial concentrations - Adsorption capacity curve The FeCuZrZnAl-MOG membrane electrode prepared in Example 5 was measured at different initial Br⁻ concentrations (200, 400, 600, 800, 1000 mg·L⁻). -1 The adsorption kinetics curves under the given conditions are shown in the figure. Figure 9 As shown in (c), the concentration decreased significantly after adsorption, with an initial concentration of 1000 mg·L⁻¹. -1 The adsorption capacity reached 123.55 mg·g. -1 .like Figure 9 As shown in (c), the Br⁻ concentration continuously decreased during the adsorption process. The initial concentration was 200 mg·L⁻¹, which decreased to 5.26 mg·L⁻¹ after adsorption. -1 Increased to 1000 mg·L-1 At that time, the adsorption capacity can reach 123.55 mg·g -1 The adsorption rate increases with increasing concentration, which is attributed to the enhanced mass transfer driving force brought about by the increased concentration gradient; the increase in equilibrium capacity proves that the material surface has sufficient active sites.

[0062] Dynamic fitting: To further investigate the rate-controlling steps of the adsorption process, pseudo-first-order, pseudo-second-order, and internal diffusion models were used to fit and analyze the adsorption kinetics data of Br⁻ in the ESIX process at different initial concentrations.

[0063]

[0064] Among them, qe and qt (mg·g -1 The values ​​of FeCuZrZnAl-MOG membrane electrode at equilibrium time and time t represent the effects of different parameters on Br. - The adsorption amount, k1(min) -1 ), k2(g·mg -1 ·min -1 ) and k d (g·mg -1 ·min 0.5 () represent the adsorption rate constants for pseudo-first-order, pseudo-second-order, and internal diffusion models, respectively. The fitting results are as follows: Figure 9 As shown in (df), the fitting results (Table 1) show that the correlation coefficient (R²) of the pseudo-second-order kinetic model is higher, indicating that the adsorption process is more in line with the model, suggesting that chemisorption may be the main rate-controlling step.

[0065] Table 1. Kinetic model simulation parameters of bromine adsorption on FeCuZrZnAl-MOG films at different initial concentrations.

[0067] Intraparticle diffusion model analysis shows that ( Figure 9 f, Table 2), Qt and t 0.5 The three-stage linear relationship reveals that the adsorption process is controlled by multi-step diffusion: the first stage is surface film diffusion; the second stage corresponds to the diffusion of Br⁻ within mesopores / macropores; and the third stage reflects the slow process of its entry into micropores or occupation of high-affinity sites. The fitted lines for each stage do not pass through the origin and are separated from each other, indicating that the adsorption process is simultaneously controlled by film diffusion and intraparticle diffusion. With increasing initial concentration, the slope of the first stage increases, reflecting that the concentration gradient enhances the driving force for film diffusion. HEMOG's high-entropy porous structure and abundant active sites provide a material basis for its high adsorption capacity.

[0068] Table 2 Characteristic parameters of the internal diffusion model

[0069] Thermodynamic analysis: The adsorption kinetics curves of FeCuZrZnAl-MOG prepared in Example 5 were determined at different initial temperatures, and the results are as follows: Figure 10 As shown, Figure 10 As shown in Table 3, the thermodynamic results further confirm that the material structure effectively promotes the chemical adsorption and interfacial reorganization of Br⁻, which is consistent with the conclusion obtained from kinetics that chemical adsorption is the rate-controlling step, thus providing theoretical support for electrochemical extraction applications.

[0070] Table 3. Simulation parameters of thermodynamic model for bromine adsorption in FeCuZrZnAl-MOG thin films at different temperatures

[0071] Example 12: Selectivity and stability of FeCuZrZnAl-MOG film electrode materials 1. Ion selectivity test The FeCuZrZnAl-MOG membrane electrode prepared in Example 5 was placed in the middle as the working electrode, with a carbon plate on each side as the counter electrode. Adsorption tests were performed on a 50 mL mixed solution of 0.5 M KBr, KF, KCl, and K2SO4 (all four substances having the same concentration) at an electrode potential of 0.3 V. The concentrations of different anions were measured, and the adsorption of the FeCuZrZnAl-MOG membrane electrode on Br2SO4 was calculated. - F - Cl - SO4 2- The selectivity.

[0072] The partition coefficient K of FeCuZrZnAl-MOG membrane electrode for each anion D (mL·g) -1 ) is calculated by the following formula (6): (6); In the formula, C0 (mg·L) -1 ) and C e (mg·L) -1 ) correspond to the initial concentration and final equilibrium concentration of anions in the solution, respectively. V (L) is the volume of the solution, and m (g) is the mass of the electroactive membrane material on the carbon felt substrate.

[0073] In addition, Br was calculated using formula (7). - (M1) Separation factor α for other anions (M2) 𝑀2 𝑀1 : (7).

[0074] The results of the ion selectivity test are as follows: Figure 11 As shown in a and Table 4, the adsorption selectivity of FeCuZrZnAl-MOG for anions is as follows: Br - >Cl - >F - SO4 2- This order is primarily derived from Br. - With a large ionic radius and low hydration energy, it is easier for it to diffuse and adsorb in the pores and active sites of materials.

[0075] Table 4. FeCuZrZnAl-MOG membrane electrode pairings with Br - Partition coefficient and separation factor with other competing anions

[0076] 2. Cyclic Voltammetry Curve Test The FeCuZrZnAl-MOG membrane electrode prepared in Example 5 was placed in the middle as the working electrode, with a carbon plate on each side as the counter electrode. The reference electrode was an Ag / AgCl electrode, and the electrolytes were 0.5M solutions of KBr, KF, KCl, and K2SO4, respectively. The electrode was operated at 5 mV·s. -1 Cyclic voltammetry curves were obtained by scanning at a rate of -0.9 to 0.9 V.

[0077] Cyclic voltammetry curves as shown Figure 11 As shown in b, in Br - The system exhibits the strongest current response and the most pronounced redox peaks, indicating optimal charge storage and reaction reversibility; while in SO4 2- The weak response in the system may be related to slow ion migration and high mass transfer resistance. These results indicate that the interactions between FeCuZrZnAl-MOG and different anions vary significantly.

[0078] 3. Desorption capacity curve test The FeCuZrZnAl-MOG membrane, which had undergone adsorption in 1000 ppm KBr solution, was reused. The electrodes were interchanged (working and counter electrodes were swapped). Desorption voltages of -0.8 V, -0.9 V, -1.0 V, -1.1 V, and -1.2 V were applied to 0.1 M sodium nitrate electrolyte solution. Solution samples were collected periodically, and the concentration of bromide ions released in the solution was determined by ion chromatography to obtain desorption capacity curves at different potentials. One adsorption-desorption cycle was counted as one cycle. Cyclic stability tests were performed on multiple adsorption-desorption cycles.

[0079] The desorption capacity curve results are as follows Figure 11 As shown in Figure c, the results indicate that as the positive potential increases (up to +1.1V), Br- The significantly increased desorption capacity indicates that anodic polarization effectively promotes ion release. This process follows an electrostatically controlled ion exchange (ESIX) mechanism: a positive potential imparts a positive charge to the material surface, and the change in oxidation state promotes ion desorption. Potential modulation provides an effective means to achieve in-situ regeneration of the material. Multiple adsorption-desorption cycle tests are performed as follows... Figure 11 As shown in d, the results indicate that FeCuZrZnAl-MOG maintains high structural stability and performance retention after continuous operation, but the adsorption capacity gradually decreases, suggesting that the active sites may undergo local passivation or structural micro-damage during long-term electrochemical cycling, and its chemical stability needs further optimization.

[0080] Example 13: Analysis of the Adsorption Performance Mechanism of FeCuZrZnAl-MOG Membrane Electrode Material 1. X-ray diffraction (XRD) analysis X-ray diffraction (XRD) analysis was performed on the FeCuZrZnAl-MOG membrane electrode material prepared in Example 5 before and after the adsorption of Br⁻ and Cl⁻. The concentrations of KBr and KCl during the adsorption of Br⁻ and Cl⁻ were 10000 PPM. The results are as follows. Figure 12 As shown in (a), the green curve represents the gel membrane electrode before ion adsorption, while the blue and yellow curves correspond to the gel membrane electrodes after chloride and bromide ion adsorption, respectively. X-ray diffraction (XRD) analysis provides crucial structural evidence for the adsorption mechanism. Before adsorption, the XRD pattern only shows a broadened diffuse scattering background without sharp Bragg diffraction peaks. This characteristic is consistent with the amorphous nature of the material. Notably, after adsorption of Br⁻ or Cl⁻, sharp diffraction peaks appeared at the same diffraction angles (23.6°, 27.4°, 29.3°, 33.7°, 44.1°), confirming that the adsorption process induced a structural phase transition from amorphous to crystalline, and that the same crystalline phase was generated. This phenomenon reveals that the essence of adsorption is strong chemical coordination. The halide anion (X⁻) first acts as a coordination template, binding with the unsaturated metal centers (Mⁿ⁺) in the gel network, inducing local order. As a crosslinking agent, it extends and locks this local order into a long-range ordered crystalline structure. The high-entropy (multimetallic) environment in this study provided diverse synergistic sites for this process, ensuring the uniqueness and stability of the final crystal structure. Therefore, the appearance of crystallization peaks in the XRD pattern is not a byproduct of adsorption, but rather direct evidence that anions trigger a fundamental structural reconstruction of the gel network through coordination crosslinking mechanisms.

[0081] 2. Fourier transform infrared spectrum Fourier transform infrared spectroscopy (FTIR) was performed on the FeCuZrZnAl-MOG membrane electrode material prepared in Example 5 before and after Br⁻ adsorption. The concentration of KBr during Br⁻ adsorption was 10000 PPM. The FTIR spectral results are shown below. Figure 12 As shown in (b), the green curve represents the gel membrane electrode before ion adsorption, and the yellow curve represents the gel membrane electrode after bromide ion adsorption. The FT-IR spectrum provides direct molecular-level evidence for the coordination and structural evolution mechanism of Br⁻. After adsorption, 3312 cm⁻¹ -1 The significant enhancement of ν(OH) at the site suggests that Br⁻ coordination may induce the formation of M-OH or strengthen the hydrogen bond network. 1634 cm⁻¹ -1 With 1384 cm -1 The synchronous enhancement of the characteristic peak of the carboxylate group confirms that Br⁻ influences the vibrational environment of the M-OOC bond through electronic effects. Most importantly, the 1040 cm⁻¹ peak, attributed to the MO bond vibration... -1 With 876 cm -1 The complete disappearance of the characteristic peaks directly confirms that Br⁻ underwent strong coordination with the metal node, and the resulting M-Br bond altered the local coordination field, causing the infrared characteristics of the original MO bond to be annihilated. Simultaneously, the fingerprint region (876-500 cm⁻¹) -1 The enhancement and complexity of the signal are evidence of increased material crystallinity and activation of MO framework vibrations. These changes collectively indicate that Br⁻, as an additional crosslinking ligand, drives the structural rearrangement and ordering of the network through strong coordination with high-entropy metal nodes. This conclusion corresponds perfectly with the appearance of crystallization peaks in XRD, jointly confirming the core mechanism of coordination-induced crystallization.

[0082] 3. Raman spectrum Raman spectroscopy was performed on the FeCuZrZnAl-MOG membrane electrode material prepared in Example 5 before and after Br⁻ adsorption. The concentration of KBr during Br⁻ adsorption was 10000 PPM. The Raman spectral results are as follows. Figure 12 As shown in (c), the green curve represents the gel membrane electrode before ion adsorption, and the yellow curve represents the gel membrane electrode after bromide ion adsorption. Raman spectroscopy provides crucial evidence at the molecular vibrational level for structural evolution. After adsorption, the characteristic peaks of the organic ligand (1001, 1405, 1471, and 2934 cm⁻¹) are observed. -1 The significant weakening or even disappearance of Br⁻ directly confirms that the strong coordination between Br⁻ and the metal center led to ligand electron cloud density rearrangement, vibrational symmetry breaking, and enhanced network rigidity. Meanwhile, ~3500 cm⁻¹ -1The significant enhancement of OH vibrations, corroborated by FT-IR results, indicates that the hydrogen bond network is synergistically strengthened during the ordering process. These molecular-scale changes are completely consistent with the M-Br bond formation (MO bond vibration annihilation) observed by FT-IR and the long-range crystallization phenomenon revealed by XRD, together forming a complete chain of evidence for the "coordination-induced crystallization" mechanism: that is, Br⁻ acts as an additional bridging ligand, driving the gel network to undergo synergistic ordering and reorganization from local chemical bonding to the overall topological structure through strong coordination.

[0083] 4. TG-DTG spectrum The FeCuZrZnAl-MOG prepared in Example 5 was subjected to TG-DTG testing, and the TG-DTG analysis results are as follows: Figure 12 As shown in (d), the results indicate that the thermal decomposition of FeCuZrZnAl-MOG exhibits a three-stage characteristic: a significant weight loss of approximately 76% within the range of room temperature to 200°C, confirming its abundant porous hydrophilic interfaces, providing channels for Br⁻ transport; a sharp DTG exothermic peak (weight loss of ~5%) between 200 and 380°C corresponds to the fracture of the organic framework, demonstrating the material's good intrinsic thermal stability at the adsorption temperature; and a broadened weight loss (~35%) after >380°C, reflecting the complex decomposition behavior of the high-entropy components. The stable amorphous network of FeCuZrZnAl-MOG below 200°C provides a necessary structural platform for the coordination and cross-linking reactions of Br⁻.

[0084] 5. XPS spectroscopy XPS spectra of the FeCuZrZnAl-MOG membrane electrode material prepared in Example 5 before and after Br⁻ adsorption are shown below. Figure 13 As shown in Figure a, the concentration of KBr during Br⁻ adsorption was 10000 PPM. The green curve represents the gel membrane electrode before ion adsorption, and the yellow curve represents the gel membrane electrode after bromide ion adsorption. The initial FeCuZrZnAl-MOG membrane contains elements such as Fe, Al, Cu, Zn, Zr, O, and C. The characteristic peak of Br appears in the oxidized state, confirming that Br⁻ is captured under the driving force of the electric field. The high-resolution Br 3d spectrum is shown below. Figure 13 b shows that the binding energy in the oxidized state belongs to the Br–M (M = Fe, Cu) coordination bond, directly proving that Br⁻ undergoes specific coordination with the metal active center. Quantitative fitting of the Fe 2p and Cu 2p spectra is as follows: Figure 13 As shown in e and 13f, this further indicates that after oxidation, Fe 2+ The proportion rose from 16.10% to 88.55%, Cu + The percentage increased from 16.84% to 66.67%, confirming the occurrence of Fe within the membrane. 3+ →Fe 2+ With Cu 2+ →Cu+ The reduction reaction. This process drives electron transfer through an external circuit. To maintain electron neutrality, Br⁻ is introduced into the gel network, thus establishing a redox-mediated conductive ion exchange (ESIX) mechanism of "potential-driven reduction-electron transfer anion intercalation". This mechanism corresponds to the Fe in CV. 3+ / Fe 2+ and Cu 2+ / Cu + The two pairs of redox peaks corroborate each other. Furthermore, the C 1s spectrum shows... Figure 13 As shown in c, the ligands remain stable before and after adsorption, indicating that the organic ligand framework is electrochemically inert and mainly serves as a structural support. The O 1s spectrum is shown below. Figure 13 As shown in d, the persistent O–M bonds confirm the integrity of the framework. The shift to lower binding energies after adsorption originates from the influence of Br⁻ coordination on the electron cloud of the M–O bonds, further supporting the coordination effect. Meanwhile, the Zn 2p, Zr 3d, and Al 2p spectra ( Figure 13 The g-13i also exhibits a consistent binding energy shift after adsorption, which indirectly reflects the strong electronic coupling effect achieved by the metal components in the high-entropy structure through oxygen bridges.

Claims

1. A method for preparing a high-entropy metal-organic gel film electrode, characterized in that, Includes the following steps: (1) Dissolve soluble metal salts in anhydrous ethanol in an equimolar ratio to prepare a metal salt solution; wherein the metal is at least five of Cu, Al, Fe, Zr, Zn, Mn, Co, Ni, Cd, and Cr; (2) Dissolve the organic ligand in anhydrous ethanol to prepare an organic ligand solution; (3) Soak the pretreated carbon felt in the metal salt solution prepared in step (1) for 12-24 h, and then put it into the organic ligand solution prepared in step (2) and let it stand for 0.5-3 h to obtain a high-entropy metal-organic gel membrane electrode.

2. The production method according to claim 1, characterized by, The metals mentioned in step (1) are Cu, Al, Fe, Zr, and Zn.

3. The production method according to claim 2, characterized by, Step (1) The total concentration of metal ions in the soluble metal salt solution is 0.5 to 2.5 mol / mL.

4. The production method according to claim 3, characterized by, In step (2), the concentration of the organic ligand is 0.05–0.25 mol / mL.

5. The preparation method according to claim 4, characterized in that, The organic ligand is one of the following: pyromellitic acid, 4,4',4''-triphenylamine tricarboxylate, 2,4,6-tris[(p-carboxyphenyl)amino]-1,3,5-triazine, 1,4-naphthalenedicarboxylic acid, tetrafluoroterephthalic acid, 2-aminoterephthalic acid, 2-(4-(1-imidazolyl)-phenyl)-imidazolium, and 2-(4-pyridyl)-imidazolium.

6. The preparation method according to claim 5, characterized in that, The organic ligand is pyromellitic acid.

7. The preparation method according to claim 1, characterized in that, Step (3) The pretreated carbon felt is obtained by immersing the carbon felt conductive substrate in 0.5 M H2SO4 solution and anhydrous ethanol for 2-6 h, then washing with anhydrous ethanol and drying.

8. A high-entropy metal-organic gel membrane electrode prepared using the preparation method described in claims 1-7.

9. The application of the high-entropy metal-organic gel membrane electrode according to claim 8 in bromide ion separation.

10. A method for separating bromide ions by electro-controlled ion exchange, characterized in that, Using the high-entropy metal-organic gel membrane electrode of claim 8 as the working electrode and the carbon plate electrode as the counter electrode, bromide ions are extracted from a bromine-containing aqueous solution.

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