A kind of using double ligand regulation synthesis metal organic gel catalyst and its preparation and application

Abstract

The application discloses a kind of using double ligand regulation synthesis metal organic gel catalyst and its preparation and application, which comprises: cobalt salt, iron salt and first ligand are dispersed in dispersing agent, second ligand is added when heating stirring, reaction and stirring at 60~100 DEG C, after reaction, cooling, aftertreatment, the double ligand regulation synthesis metal gel catalyst is prepared;The first ligand is phytic acid, citric acid, tartaric acid or thiofuran functionalized terpyridine.The application solves the problem that the pore structure in metal organic gel after pyrolysis in prior art is easy to collapse, active substance is easy to occur aggregation, which seriously affects the morphology and distribution of each active component, and greatly reduces the activity and stability.The catalyst of the application is a non-periodic structure rich in defects and has a rough surface morphology to promote the mass transfer process of oxygen on its surface and the transmission process of electric charge in its interior.

Description

Technical Field

[0001] This invention relates to a metal-organic gel catalytic material, specifically to a metal-organic gel catalyst synthesized using dual ligand regulation, and its preparation and application. Background Technology

[0002] The extensive use of fossil fuels has created two major problems: energy shortages and environmental pollution, leading to a series of crises. Therefore, there is an urgent need to develop clean, pollution-free, sustainable, and high-energy-density new energy sources to replace the dwindling traditional fossil fuels. Metal-air batteries are devices that convert chemical energy into electrical energy through the oxidation of metals and the reduction of oxygen in the air. Flexible zinc-air batteries (FZABs) have high energy density and safety, are portable and convenient, and are environmentally friendly, showing broad application prospects in portable wearable electronics. The performance of FZABs is closely related to the electrode reactions, especially the slow kinetics of the four-electron-dominated cathode hydrogen reduction reaction (ORR) and oxygen evolution reaction (OER). The high overpotential of the reaction leads to low energy efficiency of FZABs, and the reaction rate is heavily dependent on the cathode catalyst. Currently, commonly used ORR / OER catalysts are mainly oxides of Pt and Ir / Ru, which are expensive and prone to poisoning, severely limiting the cost, performance, and lifespan of the batteries. To further improve the performance of flexible zinc-air batteries and advance their commercialization, it is urgent to develop inexpensive and efficient non-precious metal ORR / OER bifunctional catalysts.

[0003] Organometallic gels (MOGs) are gels formed by introducing metal ions into supramolecular organic gels, utilizing the coordination between metal ions and organic ligands, or by using metal complexes as gelling agents to fix solvent molecules through non-covalent interactions. MOGs possess controllable metal coordination, tunable organic ligands, numerous Lewis sites, and porous structures, making them highly valuable for electrocatalysis. Typically, metal, carbon, and nitrogen sources are introduced into the MOG gel matrix, and pyrolysis yields catalytic materials with metal nanoparticles dispersed in nitrogen-doped carbon, exhibiting certain ORR activity. Further adjustments to the metal types and ratios yield trimetallic Co / Fe / Ni-MOGs; the pyrolyzed catalysts possess abundant active sites and interfaces, effectively regulating the electronic structure of each component. However, the pore structure in organometallic gels is prone to collapse after pyrolysis, and active materials are easily aggregated, severely affecting the morphology and distribution of active components, significantly reducing activity and stability, and limiting the development of ZABs technology to some extent. Summary of the Invention

[0004] The purpose of this invention is to provide a metal-organic gel catalyst synthesized using dual-ligand regulation, and its preparation and application. This invention solves the problems of easy collapse of the pore structure and easy aggregation of active substances in metal-organic gels after pyrolysis in the prior art, which seriously affects the morphology and distribution of each active component and causes a significant decrease in activity and stability.

[0005] To achieve the above objectives, the present invention provides a method for preparing a metal-organic gel catalyst using dual-ligand regulation, the method comprising:

[0006] Cobalt salt, iron salt, and the first ligand are dispersed in a dispersant. The second ligand is added while heating and stirring. The reaction is carried out at 60–100 °C with stirring. After the reaction is completed, the mixture is cooled and post-processed to obtain the metal gel catalyst synthesized using dual ligand regulation. The first ligand is phytic acid, citric acid, tartaric acid, or thiophene-functionalized terpyridine. The second ligand is 2,4,6-tris[(p-carboxyphenyl)amino]-1,3,5-triazine, terephthalic acid, thiophene-functionalized terpyridine, pyromellitic acid, pyrazole, p-methylbenzoic acid, or pyromellitic acid.

[0007] Preferably, the cobalt salt is cobalt nitrate hexahydrate, cobalt acetate hexahydrate, cobalt sulfate tetrahydrate, or cobalt chloride hexahydrate.

[0008] Preferably, the iron salt is ferric nitrate nonahydrate, ferric acetate nonahydrate, ferric sulfate tetrahydrate, or ferric chloride nonahydrate.

[0009] Preferably, the dispersant is N,N-dimethylformamide, water, ethylene glycol, ethanol, or methanol.

[0010] Preferably, the molar ratio of the cobalt salt to the iron salt is (1-5):1.

[0011] Preferably, the molar ratio of the first ligand to the total molar ratio of the cobalt and iron salts is 1:(1-10); the molar ratio of the second ligand to the total molar ratio of the cobalt and iron salts is 1:(1-10). By controlling the molar ratio of the total metal salt to the first ligand to be 1:(1-10) (the total molar ratio of the metal salt to the first ligand is in excess), a metal-organic gel with unsaturated coordination between the metal central atom and the phytic acid ligand is obtained. When the second ligand is introduced, N coordination can be introduced at the active sites on the catalyst surface, adjusting the electronic structure of the central atom. Furthermore, the semi-flexible structure of the second ligand can enable the catalyst to obtain a larger specific surface area, promote the exposure of active sites, and enhance the bifunctional catalytic activity.

[0012] More preferably, the molar ratio of the cobalt salt to the iron salt is 3:1. The catalyst prepared when the molar ratio of the cobalt salt to the iron salt is 3:1 has the best performance, possibly because the coordination of the iron salt can change the coordination environment of the cobalt at the center, which is the catalytic active center, thereby changing the charge distribution around it, optimizing the adsorption energy of the intermediate, and thus improving the catalytic activity.

[0013] Preferably, the post-treatment involves centrifugal washing with a dispersant and deionized water, followed by vacuum drying at 80°C and then grinding.

[0014] Preferably, the reaction time is 1 to 3 hours, and the stirring time is 1 hour.

[0015] This invention provides a metal-organic gel catalyst prepared by the method described above, using dual-ligand controlled synthesis.

[0016] This invention provides an application of the catalyst as described above in a flexible zinc-air battery.

[0017] This invention discloses a metal-organic gel catalyst synthesized using dual-ligand regulation, its preparation, and its application. It solves the problems of easy collapse of the pore structure and easy aggregation of active substances in metal-organic gels after pyrolysis in existing technologies, which severely affect the morphology and distribution of each active component, leading to a significant decrease in activity and stability. It has the following advantages:

[0018] (1) The present invention employs a simple and easy method to obtain a metal-organic gel bifunctional catalyst by regulating the first ligand and the second ligand. The catalyst has a defect-rich non-periodic structure and a rough surface morphology to promote the mass transfer process of oxygen on its surface and the charge transport process inside it.

[0019] (2) The introduction of a second ligand in this invention alters the coordination environment, providing more abundant coordination sites for the central atom. This allows for adjustment of the charge density of catalytically active metal ions, changing the adsorption energy of oxygen reduction and oxygen evolution reaction intermediates, and lowering the reaction energy barrier. Simultaneously, the second ligand, as a semi-flexible ligand, possesses a variable coordination mode, providing the organometallic gel with a richer pore structure and a larger specific surface area, promoting the exposure of active sites, enhancing bifunctional catalytic activity, and ensuring the stability of the organometallic gel during the catalytic process.

[0020] (3) Experimental results on oxygen reduction and oxygen evolution in 1M KOH showed that the catalyst of the present invention exhibits an increase in the oxygen reduction half-wave potential and limiting current density in an alkaline environment, as well as a lower overpotential in the oxygen evolution reaction. Furthermore, application results in flexible zinc-air batteries show that the catalyst of the present invention can effectively improve the power density and extend the discharge time of flexible zinc-air batteries. Attached Figure Description

[0021] Figure 1 This is an electron micrograph of the catalyst prepared in Example 1 of the present invention;

[0022] Figure 2 This is an elemental distribution analysis diagram of Embodiment 1 of the present invention after electrode performance testing;

[0023] Figure 3 The X-ray diffraction pattern of the catalyst prepared in Example 1 of this invention;

[0024] Figure 4 The nitrogen adsorption-desorption curve and pore size distribution of the catalyst prepared in Example 1 of this invention are shown.

[0025] Figure 5 Fourier transform infrared spectra of the catalyst, phytic acid ligand, and H3TATAB ligand prepared in Example 1 of this invention;

[0026] Figure 6 The X-ray photoelectron spectrum of the catalyst prepared in Example 1 of this invention;

[0027] Figure 7 A comparison of polarization curves of the catalyst of Example 1, the catalyst of Comparative Example 1, and the electrode prepared from commercial IrO2 in the oxygen evolution reaction.

[0028] Figure 8 A comparison of polarization curves of electrodes prepared with catalysts from Example 1 and Comparative Example 1 of the present invention in the oxygen reduction reaction;

[0029] Figure 9 The polarization curves and corresponding power density curves of flexible zinc-air batteries composed of Example 1 of the present invention and commercial Pt / C+IrO2 are shown.

[0030] Figure 10 The constant current discharge curves of flexible zinc-air batteries composed of Example 1 of the present invention and commercial Pt / C+IrO2 are shown.

[0031] Figure 11 Comparison of oxygen reduction and oxygen evolution reaction polarization curves for electrodes prepared with the catalysts of Examples 1, 2 and 3 of this invention. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] A method for preparing a metal-organic gel catalyst using dual-ligand regulation, the method comprising (coordinating phytic acid with Co and Fe, and then introducing a second ligand H3TATAB for further coordination):

[0035] (1) Dissolve 0.2323 g of cobalt nitrate tetrahydrate, 0.3232 g of ferric nitrate tetrahydrate, and 0.528 g of phytic acid in 40 mL of N,N-dimethylformamide, respectively, and stir magnetically for 30 min at room temperature to disperse evenly, to obtain cobalt nitrate tetrahydrate solution, ferric nitrate tetrahydrate solution, and phytic acid solution, respectively; disperse 0.389 g of H3TATAB in 40 mL of deionized water, sonicate for 30 min, and continue stirring for 30 min to obtain H3TATAB solution;

[0036] (2) Take 15 mL of cobalt nitrate tetrahydrate solution, 5 mL of ferric nitrate tetrahydrate solution and 5 mL of phytic acid solution obtained in step (1) and add them dropwise to a beaker. Stir at 80°C for 1 h to obtain the reaction solution.

[0037] (3) Add 5 mL of H3TATAB solution obtained in step (1) dropwise to the reaction solution obtained in step (2), heat to 80°C, and keep stirring at 80°C for 1 hour (the molar ratio of phytic acid in phytic acid solution, H3TATAB, cobalt in cobalt nitrate tetrahydrate solution and iron in ferric nitrate tetrahydrate solution is 1:1:3:1).

[0038] (4) After the reaction in step (3) is completed, cool to room temperature, wash repeatedly by centrifugation three times with N,N-dimethylformamide, methanol and deionized water, dry in a vacuum oven at 60°C for 12 hours, grind, and obtain the metal organogel catalyst (PA-H3TATAB-Co / Fe) synthesized by dual ligand regulation.

[0039] Comparative Example 1

[0040] A method for preparing a catalyst, which is basically the same as that in Example 1, except that:

[0041] In step (1), it is not necessary to prepare the H3TATAB solution;

[0042] Step (3) is missing;

[0043] The catalyst was obtained by the same procedure as in Example 1.

[0044] Comparative Example 2

[0045] A method for preparing a catalyst, which is basically the same as that in Example 1, except that:

[0046] In step (1), it is not necessary to prepare a phytic acid solution;

[0047] In step (2), no phytic acid solution is added;

[0048] The same procedure as in Example 1 could not yield a metal-organic gel catalyst.

[0049] Example 2

[0050] The preparation method of a metal-organic gel catalyst using dual-ligand regulation is basically the same as that in Example 1, except that:

[0051] In step (1), 0.389g of H3TATAB is replaced with 0.133g of terephthalic acid to prepare a terephthalic acid solution;

[0052] In step (3), 5 mL of H3TATAB solution is replaced with 5 mL of terephthalic acid solution.

[0053] Example 3

[0054] A method for preparing a metal-organic gel catalyst using dual-ligand regulation, the method comprising:

[0055] 100 mg of cobalt nitrate hexahydrate, 100 mg of H3TATAB and 100 mg of thiophene-functionalized terpyridine were dissolved in 40 mL of N,N-dimethylformamide and then transferred to a hydrothermal reactor. The reaction was carried out at 140 °C for 24 h. The mixture was washed three times by centrifugation with N,N-dimethylformamide, methanol and deionized water. The mixture was then dried in a vacuum oven at 60 °C for 12 h and ground to obtain a metal-organic gel catalyst for synthesis controlled by dual ligands.

[0056] Characterization of the catalyst prepared in Example 1 of Experiment 1

[0057] 1. Electron microscopy analysis

[0058] Electron microscopy analysis was performed on the catalyst prepared in Example 1 of this invention, and the results are detailed in [the table below]. Figure 1 .

[0059] like Figure 1 The image shown is an electron microscope image of the catalyst prepared in Example 1 of this invention. Figure 1 As can be seen, the catalyst prepared in Example 1 of this invention has a bulk structure with dot-like substances precipitated on its surface. The uneven surface structure of the catalyst can provide a larger contact area for the reactants and expose more catalytic active sites, thereby promoting the oxygen reduction reaction and the oxygen evolution reaction.

[0060] 2. Elemental Distribution Analysis

[0061] Elemental distribution analysis was performed on the catalyst prepared in Example 1 of this invention after electrode performance testing. The results are detailed in [link to relevant documentation]. Figure 2 .

[0062] like Figure 2 The figure shown is an elemental distribution analysis diagram of Embodiment 1 of the present invention after electrode performance testing. Figure 2 It can be seen that the Co and Fe elements in the catalyst after the reaction of the present invention are uniformly dispersed, indicating that the metal organogel has a stable structure and the active substances are not prone to agglomeration during the reaction process.

[0063] 3. X-ray diffraction analysis

[0064] X-ray diffraction analysis was performed on the catalyst prepared in Example 1 of this invention, and the results are detailed in [the table below]. Figure 3 .

[0065] like Figure 3 The image shows the X-ray diffraction pattern of the catalyst prepared in Example 1 of this invention. Figure 3 As can be seen, there are no obvious diffraction peaks in the figure, indicating that the metal-organic gel catalyst prepared in Example 1 has an amorphous structure. Compared with metal-organic framework systems with periodic structures, the catalyst of the present invention has a non-periodic structure, indicating that the catalyst of the present invention has abundant defects and favorable charge transfer processes, thereby reducing the reaction energy barrier and improving catalytic activity.

[0066] 4. Nitrogen adsorption-desorption analysis

[0067] The catalyst prepared in Example 1 of this invention was subjected to nitrogen adsorption-desorption analysis, and the results are detailed in [the table below]. Figure 4 .

[0068] like Figure 4 As shown, the nitrogen adsorption-desorption curve and pore size distribution diagram of the catalyst prepared in Example 1 of this invention are presented. Figure 4 It can be seen that the specific surface area of ​​the catalyst is 89.98 m². 2 ·g -1 Most of the pores are concentrated around 3.7 nm, indicating that the catalyst prepared in Example 1 of this invention has a rich mesoporous structure, thanks to the regulation of phytic acid ligands and H3TATAB ligands. The pore structure of Example 1 is beneficial to improving the diffusion of oxygen molecules on the catalyst surface, making it easier for oxygen to be adsorbed and desorbed around the catalytic sites, thereby promoting the oxygen catalysis process.

[0069] 5. Fourier transform infrared spectroscopy analysis

[0070] Fourier transform infrared spectroscopy analysis was performed on the catalyst prepared in Example 1 of this invention, and the results are detailed in [link to article]. Figure 5 .

[0071] like Figure 5 The image shows the Fourier transform infrared spectra of the catalyst, phytic acid ligand, and H3TATAB ligand prepared in Example 1 of this invention. Figure 5It can be seen that the catalyst prepared in Example 1 has a viscosity of 3411 cm⁻¹. -1 The peak at 3600 to 2800 cm⁻¹ corresponds to the stretching vibration peak of -NH⁻, which originates from the -NH group in the H₃TATAB ligand. -1 The broad stretching vibration peaks are attributed to the stretching of the -OH group, likely due to the coordination of the central atom leading to ligand stretching, thus shifting the -OH vibration peak to longer wavelengths. Compared to the H3TATAB ligand, the gel-formed PA-H3TATAB-Co / Fe also exhibits stretching vibration peaks (~1387 cm⁻¹) from the -CO- single bond of the H3TATAB ligand. -1 The stretching vibration peak of PO from phytic acid ligand (~1060 cm⁻¹) and the peak of PO stretching vibration from phytic acid ligand (~1060 cm⁻¹) -1 This indicates that the introduction of the second ligand H3TATAB resulted in a certain amount of stretching and contraction of the semi-flexible H3TATAB ligand, which promoted the formation of the metal-organic gel.

[0072] 6. X-ray photoelectron spectroscopy analysis

[0073] X-ray photoelectron spectroscopy analysis was performed on the catalyst prepared in Example 1 of this invention, and the results are detailed in [link to details]. Figure 6 .

[0074] like Figure 6 The X-ray photoelectron spectrum of the catalyst prepared in Example 1 of this invention is shown below, where (a) is the full spectrum of the catalyst; (b) is the partial spectrum of phosphorus; (c) is the partial spectrum of oxygen; (d) is the partial spectrum of nitrogen; (e) is the partial spectrum of cobalt; and (f) is the partial spectrum of iron. Figure 6 As can be seen from (a), the catalyst is mainly composed of six elements: Co, Fe, O, N, C, and P. From... Figure 6 From (b), we know that phosphorus originates from phytic acid ligands and exists in the form of PO, without participating in the coordination process of the central atom. From Figure 6 As can be seen in (c), oxygen exists in the organometallic gel in the forms of -OH and -COOH. From Figure 6 From (d), we know that nitrogen in H3TATAB participates in coordination and forms a Co-N coordination bond, thereby harmonizing the electronic structure of the central atom and facilitating the formation of surface defects and aperiodic structures. Figure 6 As can be seen from (e) and (f), both cobalt and iron exist in the +2 oxidation state in the organometallic gel.

[0075] 7. Performance analysis of the prepared electrodes

[0076] The oxygen reduction reaction and oxygen evolution reaction performance tests were conducted as follows: The catalysts prepared in Example 1 and Comparative Example 1 were modified onto the working electrode using a three-electrode system. A carbon rod was used as the counter electrode, Hg / HgO as the reference electrode, and a platinum-carbon electrode as the working electrode. The electrolyte was 1M KOH. 5 mg of the sample to be tested (the electrode modified with the catalysts prepared in Example 1 and Comparative Example 1) and 5 mg of acid-treated acetylene black were added to 0.5 mL of a 1:1 mixture of deionized water and anhydrous ethanol. Then, 50 μL of Nafion solution (perfluorosulfonic acid polymer solution) was added, and the mixture was sonicated for 30 min to ensure thorough and uniform dispersion. 15 μL of the uniformly dispersed catalyst slurry was pipetted onto a polished platinum-carbon electrode and allowed to dry. Test conditions: rotating disk electrode, O2-saturated 1M KOH, scan rate 10 mV·s. -1 The rotation speed is 1600 rpm, and the oxygen reduction reaction test voltage range is 0.2V to -1V relative to the standard hydrogen electrode potential; the oxygen evolution reaction performance test voltage range is 0V to 1V relative to the standard hydrogen electrode potential.

[0077] like Figure 7 The figure shows a comparison of the polarization curves of the catalyst of Example 1, the catalyst of Comparative Example 1, and the electrode prepared from commercial IrO2 in the oxygen evolution reaction. The current density is 10 mA·cm. -2 The corresponding potential is considered an important parameter for evaluating the catalytic activity of the oxygen evolution reaction. (By...) Figure 7 As can be seen, Example 1 exhibits superior oxygen evolution activity compared to Comparative Example 1, with an overpotential of only 257 mV. This indicates that the semi-flexible H3TATAB ligand promotes the formation of unsaturated coordination of the central atoms on the surface of the organometallic gel catalyst, providing more active sites and thus achieving better catalytic activity. The above results demonstrate that the catalyst of the present invention possesses excellent dual-function catalytic activity for both oxygen reduction and oxygen evolution.

[0078] like Figure 8 The figure shows a comparison of the polarization curves of the electrodes prepared with the catalysts of Example 1 and Comparative Example 1 in the oxygen reduction reaction. From... Figure 8 It can be seen that the limiting current density of the electrode prepared by the catalyst in Example 1 of this invention is 6 mA·cm⁻¹. -2 The initial potential was 0.93 V, and the half-wave potential was 0.78 V. Compared with Comparative Example 1, the electrode prepared by the catalyst in Example 1 of this invention exhibits superior oxygen reduction performance. This indicates that the addition of the second ligand H3TATAB of this invention introduces coordination effects other than MO, thereby altering the electron configuration around the central atom, generating non-periodic atomic misalignment and unsaturated coordination sites for surface metal atoms, thus obtaining richer active sites conducive to the oxygen reduction reaction.

[0079] The flexible zinc-air battery test process is as follows: The flexible zinc-air battery test device uses a polished 0.05 mm zinc foil as the anode, and carbon cloth coated with a catalyst (the catalyst of Example 1, commercial Pt / C+IrO2) is loaded (1 mg of catalyst is loaded on a 1×1 cm² substrate using conventional methods in the art). 2 Commercial carbon cloth was used as the air cathode, and the solid electrolyte was polyacrylic acid with 11M KOH. A mixture of commercial Pt / C and IrO2 at a mass ratio of 1:1 was used as a control sample, and tests were conducted under the same conditions. The specific preparation method of the solid electrolyte was as follows: 18g of potassium hydroxide was dissolved in 26mL of deionized water, and then 3g of polyacrylic acid and 0.5g of N,N'-methylenebisacrylamide were added, stirred, and filtered. The clear liquid was then added to 50μL of saturated potassium persulfate solution, stirred rapidly, and then placed in a mold to solidify into a gel electrolyte for later use.

[0080] like Figure 9 As shown, the polarization curves and corresponding power density curves of flexible zinc-air batteries composed of Embodiment 1 of the present invention and commercial Pt / C+IrO2 are respectively presented. Figure 9 It can be seen that the peak power density obtained by using Example 1 as the cathode catalyst of the flexible zinc-air battery is 98.03 mW·cm⁻¹. -2 This is far higher than that of commercial catalysts (35.78 mW·cm⁻¹). -2 ).

[0081] like Figure 10 As shown, the constant current discharge (2 mA·cm⁻¹) of a flexible zinc-air battery composed of Example 1 of the present invention and commercial Pt / C+IrO₂ is demonstrated. -2 (Line graph.) Figure 10 It can be seen that the flexible zinc-air battery assembled in Example 1 has a discharge time of up to 14 hours and can maintain a stable discharge voltage platform. Its overall performance in the battery is better than that of the commercial catalyst Pt / C+IrO2.

[0082] like Figure 11 The diagram shows a comparison of the oxygen reduction and oxygen evolution reaction polarization curves corresponding to the electrodes prepared with the catalysts of Examples 1, 2, and 3 of this invention, where (a) represents oxygen evolution and (b) represents oxygen reduction. Figure 11As can be seen, Example 1 exhibits superior oxygen reduction and oxygen evolution activity compared to Examples 2 and 3. Therefore, compared to thiophene-functionalized terpyridine with a thiophene group and terephthalic acid with only rigidity, the H3TATAB used as a semi-flexible ligand in Example 1 of this invention can give the metal-organic gel a higher specific surface area and a richer pore structure, providing more channels for mass transfer. Furthermore, the amino group in H3TATAB can provide nitrogen coordination sites for the central atom. At the same time, the phytic acid ligand can provide abundant oxygen coordination sites, which, together with the nitrogen sites, affect the coordination environment of the central atom, thereby optimizing the electronic structure of the central atom and changing the adsorption energy of the oxygen reduction and oxygen evolution reaction intermediates. As a result, the catalyst of Example 1 exhibits excellent electrochemical performance.

[0083] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a metal-organic gel catalyst using dual-ligand controlled synthesis, characterized in that, The method includes: Cobalt salt, iron salt and the first ligand are dispersed in a dispersant, heated and stirred, and then the second ligand is added. The reaction is carried out at 60-100 °C and stirred. After the reaction is completed, the mixture is cooled and post-processed to obtain the metal gel catalyst synthesized using dual ligand regulation. The first ligand is phytic acid, citric acid, tartaric acid, or thiophene-functionalized terpyridine; The second ligand is 2,4,6-tris[(p-carboxyphenyl)amino]-1,3,5-triazine, terephthalic acid, thiophene-functionalized terpyridine, pyromellitic acid, pyrazole, p-methylbenzoic acid, or pyromellitic acid.

2. The method according to claim 1, characterized in that, The cobalt salt is cobalt nitrate hexahydrate, cobalt acetate hexahydrate, cobalt sulfate tetrahydrate, or cobalt chloride hexahydrate.

3. The method according to claim 1, characterized in that, The iron salt is ferric nitrate nonahydrate, ferric acetate nonahydrate, ferric sulfate tetrahydrate, or ferric chloride nonahydrate.

4. The method according to claim 1, characterized in that, The dispersant is N,N-dimethylformamide, water, ethylene glycol, ethanol, or methanol.

5. The method according to claim 1, characterized in that, The molar ratio of the cobalt salt to the iron salt is (1-5):

1.

6. The method according to claim 1, characterized in that, The amount of the first ligand is in the same ratio as the total amount of cobalt and iron salts, which is 1:(1-10); the amount of the second ligand is in the same ratio as the total amount of cobalt and iron salts, which is 1:(1-10).

7. The method according to claim 1, characterized in that, The post-treatment involves centrifugation and washing with a dispersant and deionized water, followed by vacuum drying at 80 °C and grinding.

8. The method according to claim 1, characterized in that, The reaction time is 1-3 h.

9. A metal-organic gel catalyst prepared by the method according to any one of claims 1-8 using dual-ligand controlled synthesis.

10. The application of the catalyst as described in claim 9 in a flexible zinc-air battery.

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