Double-sided membrane catalytic electrode and preparation method and catalytic degradation of pollutant system in water thereof

Abstract

The application provides a double-sided membrane catalytic electrode, a preparation method thereof and a catalytic degradation system of pollutants in water. The double-sided membrane catalytic electrode comprises a carbon skeleton fiber, the carbon skeleton fiber has a first surface and a second surface arranged oppositely, the first surface is loaded with first transition metal monomers, the second surface is loaded with second transition metal monomers, one of the first transition metal monomers and the second transition metal monomers is used for inducing generation of oxidizing active species, and the other is used for inducing generation of reducing active species. Redox synergy can be achieved, so that the energy barrier of the reaction is reduced, and the reaction efficiency is improved; the two different metal monomers are spatially partitioned, so that the quenching reaction between the active species is effectively reduced, and the reaction efficiency is improved; the reaction sequence of pollutants in the two surfaces of the double-sided membrane catalytic electrode can be adjusted by changing the flow direction of sewage, so that adjustable redox is achieved, and new pollutants in sewage can be efficiently removed.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a double-film catalytic electrode, its preparation method, application, and system for catalytic degradation of pollutants in water. Background Technology

[0002] Emerging pollutants refer to toxic and hazardous chemical substances characterized by biotoxicity, environmental persistence, and bioaccumulation. These primarily include persistent organic pollutants (POPs), endocrine disruptors, and antibiotics, which are regulated by international conventions. The discharge of emerging pollutants into wastewater further exacerbates the water crisis and poses potential hazards to human health. Electrochemical advanced oxidation-reduction (ERR) is a promising technology for advanced wastewater treatment, offering advantages such as high reactivity, environmental friendliness, and modular design. However, oxidation alone is insufficient for efficiently removing organic matter containing electron-withdrawing groups, and reduction alone is insufficient for mineralizing organic matter. Existing technologies are ill-suited for the efficient removal of various emerging pollutants. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, one object of this invention is to provide a dual-film catalytic electrode that can effectively reduce quenching reactions between active species, achieve in-situ redox synergy, and thus effectively remove various types of new pollutants from wastewater.

[0004] In one aspect, the present invention provides a dual-film catalytic electrode. According to an embodiment of the invention, the dual-film catalytic electrode comprises carbon skeleton fibers having a first surface and a second surface disposed opposite to each other. The first surface is loaded with a first transition metal single atom, and the second surface is loaded with a second transition metal single atom. One of the first and second transition metal single atoms is used to induce the generation of an oxidizing active species, and the other is used to induce the generation of a reducing active species. Thus, the first and second transition metal single atoms in the dual-film catalytic electrode can respectively induce the generation of oxidizing and reducing active species, achieving redox synergy, thereby lowering the energy barrier of the reaction and improving reaction efficiency. Furthermore, the first and second transition metal single atoms are located on the two surfaces of the dual-film catalytic electrode, with a certain distance between the two different metal single atoms, i.e., spatial partitioning, which can effectively reduce quenching reactions between active species, thereby further contributing to improved reaction efficiency. Therefore, applying the above-mentioned double-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Moreover, since the first and second transition metal single atoms can induce the generation of oxidative and reductive active species, respectively, the reaction sequence of pollutants on the two surfaces of the double-film catalytic electrode can be adjusted by changing the wastewater flow direction according to different types of new pollutants, thereby achieving adjustable oxidation-reduction and efficiently removing new pollutants from wastewater.

[0005] According to an embodiment of the present invention, the transition metal single atom includes at least one of iron, nickel, copper, cobalt, zinc, and manganese, and the coordinating atom coordinated with the transition metal includes at least one of nitrogen, phosphorus, sulfur, and oxygen, and the number of coordinating atoms coordinated with one transition metal single atom is 1 to 6.

[0006] According to embodiments of the present invention, the oxidizing active species includes one or more of hydroxyl radicals, sulfate radicals, or singlet oxygen, and the reducing active species includes one or two of atomic hydrogen and hydrated electrons.

[0007] In another aspect, the present invention provides a method for preparing the aforementioned dual-film catalytic electrode. According to an embodiment of the present invention, the method for preparing the dual-film catalytic electrode includes: uniformly mixing a first polymer, a first transition metal single-atom precursor, and a first organic solvent to obtain a first spinning solution; uniformly mixing a second polymer, a second transition metal single-atom precursor, and a second organic solvent to obtain a second spinning solution; performing a first electrospinning using the first spinning solution for a period of time, then replacing the second spinning solution to continue a second electrospinning process to obtain a dual-film intermediate; pre-oxidizing the dual-film intermediate to obtain a pre-oxidized dual-film; and carbonizing the pre-oxidized dual-film to obtain a dual-film catalytic electrode. Therefore, in the double-film catalytic electrode prepared by the above method, the first and second transition metal single atoms can respectively induce the generation of oxidative and reductive active species, achieving redox synergy, thereby reducing the energy barrier of the reaction and improving the reaction efficiency. Furthermore, the first and second transition metal single atoms are located on the two surfaces of the double-film catalytic electrode, with a certain distance between the two different transition metal single atoms, which can effectively reduce quenching reactions between active species, further contributing to improved reaction efficiency. Therefore, applying the above-mentioned double-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Moreover, since the first and second transition metal single atoms can respectively induce the generation of oxidative and reductive active species, the order in which wastewater flows to the two surfaces of the double-film catalytic electrode can be adjusted according to different types of new pollutants, achieving better in-situ redox synergy and thus efficiently removing new pollutants from wastewater.

[0008] According to an embodiment of the present invention, the first transition metal single-atom precursor includes at least one of a metal-organic framework compound containing the first transition metal, a phthalocyanine salt containing the first transition metal, a mixture of a transition metal salt containing the first transition metal and a first organic compound, and the second transition metal single-atom precursor includes at least one of a metal-organic framework compound containing the second transition metal, a phthalocyanine salt containing the second transition metal, or a mixture of a transition metal salt containing the second transition metal and a second organic compound.

[0009] According to an embodiment of the present invention, the mass ratio of the first polymer to the first transition metal single-atom precursor is 1:0.01 to 1:3; the mass ratio of the second polymer to the second transition metal single-atom precursor is 1:0.01 to 1:3.

[0010] According to embodiments of the present invention, the first spinning solution is prepared by the following method A, method B, or method C: Method A: Zinc nitrate and a first transition metal salt are dissolved in a solvent, and then a 2-methylimidazole solution is added to the mixture to obtain a mixed solution. The mixed solution is stirred, separated, and dried to obtain the metal-organic framework compound containing the first transition metal. The metal-organic framework compound containing the first transition metal, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution; Method B: The phthalocyanine salt containing the first transition metal, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution; Method C: The first transition metal salt, the first organic compound, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution, wherein the first organic compound includes at least one of phenanthroline and dopamine.

[0011] The second spinning solution is prepared by one of the following methods: D, E, or F: Method D: Zinc nitrate and a second transition metal salt are dissolved in a solvent, and then a 2-methylimidazole solution is added to the mixture. After stirring, separation, and drying, the metal-organic framework compound containing the second transition metal is obtained; the metal-organic framework compound containing the second transition metal, the second polymer, and the second organic solvent are uniformly mixed to obtain the second spinning solution; Method E: The phthalocyanine salt containing the second transition metal, the second polymer, and the second organic solvent are uniformly mixed to obtain the second spinning solution; Method F: The second transition metal salt, the second organic compound, the second polymer, and the second organic solvent are uniformly mixed to obtain the second spinning solution, wherein the second organic compound includes at least one of phenanthroline and dopamine.

[0012] According to an embodiment of the present invention, at least one of the following conditions is met in method A: the first transition metal salt includes at least one of nitrate and acetylacetonate; the ratio of the first transition metal salt to the solvent is (0.05-5) mmol: 100 mL; in the first spinning solution, the amount of the metal-organic framework compound added is 0.08-0.12 g / mL of the first organic solvent, and the amount of the first polymer added is 0.08-0.12 g / mL of the first organic solvent;

[0013] In method B, at least one of the following conditions is met: in the first spinning solution, the amount of phthalocyanine salt added is 0.01 to 0.2 mmol / mL of the first organic solvent, and the amount of the first polymer added is 0.08 to 0.12 g / mL of the first organic solvent;

[0014] In method C, at least one of the following conditions is met: the first transition metal salt includes at least one of nitrate and acetylacetone salt; in the first spinning solution, the amount of the first transition metal salt added is 0.01 to 0.1 mmol / mL of the first organic solvent, the molar ratio of the first organic compound to the first transition metal salt is 4:1 to 8:1, and the amount of the first polymer added is 0.08 to 0.12 g / mL of the first organic solvent;

[0015] In method D, at least one of the following conditions is met: the second transition metal salt includes at least one of nitrate and acetylacetonate; the ratio of the second transition metal salt to the solvent is (0.05-5) mmol: 100 mL; in the second spinning solution, the amount of the metal-organic framework compound added is 0.08-0.12 g / mL of the second organic solvent, and the amount of the second polymer added is 0.08-0.12 g / mL of the second organic solvent;

[0016] In method E, at least one of the following conditions is met: in the second spinning solution, the amount of phthalocyanine salt added is 0.01 to 0.2 mmol / mL of the second organic solvent, and the amount of the second polymer added is 0.08 to 0.12 g / mL of the second organic solvent;

[0017] In method F, at least one of the following conditions is met: the second transition metal salt includes at least one of nitrate and acetylacetone salt; in the second spinning solution, the amount of the second transition metal salt added is 0.01 to 0.1 mmol / mL of the second organic solvent, the molar ratio of the second organic compound to the second transition metal salt is 4:1 to 8:1, and the amount of the second polymer added is 0.08 to 0.12 g / mL of the second organic solvent.

[0018] According to an embodiment of the present invention, the conditions for the pre-oxidation treatment include: a temperature of 240–300°C and a time of 0.5–3 h; the conditions for the carbonization treatment include: a temperature of 600–1400°C and a time of 0.5–3 h.

[0019] In another aspect, the present invention provides an application of the aforementioned dual-film catalytic electrode in the degradation of pollutants. Thus, applying the above-mentioned dual-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Since the first and second transition metal single atoms can respectively induce the generation of oxidative and reductive species, the order in which wastewater flows to the two surfaces of the dual-film catalytic electrode can be adjusted according to different types of new pollutants, thereby achieving better in-situ synergistic oxidation-reduction and efficiently removing new pollutants from the wastewater.

[0020] In another aspect, the present invention provides a system for catalytically degrading pollutants in water. According to embodiments of the present invention, the system for catalytically degrading pollutants includes: an anode; and a cathode, wherein the cathode is the aforementioned double-film catalytic electrode, or the double-film catalytic electrode prepared by the aforementioned method. Thus, this system can effectively remove various new pollutants from wastewater.

[0021] According to an embodiment of the present invention, during the degradation of the pollutants, the voltage between the anode and the cathode is 0.5–5V at normal temperature and pressure, and the membrane flux of the wastewater is 50–2000 L / m³. -2 h -1 .

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 The graph shows the test results of the catalytic degradation system for pollutants in Examples 1-1, 1-2, and 1-3 for the degradation of propranolol (PRO) in wastewater.

[0025] Figure 2 The graph shows the test results of the catalytic degradation system for pollutants in Examples 1-1, 1-4, and 1-5 for the degradation of propranolol (PRO) in wastewater.

[0026] Figure 3 This is a schematic diagram of the double-film catalytic electrode after the wastewater has been degraded in Examples 1-4;

[0027] Figure 4 The graphs show the test results of the catalytic degradation systems for pollutants in Examples 2-1, 2-2, 2-3 and Comparative Example 2-1 for the degradation of propranolol (PRO) in wastewater.

[0028] Figure 5 This is the tensile stress-strain curve of the double-film catalytic electrode in Example 3-1;

[0029] Figure 6a This is an electron microscope image of the double-film catalytic electrode in Example 3-1;

[0030] Figure 6b These are scanning electron microscope images of iron-containing and nickel-containing metal-organic framework compound powders.

[0031] Figure 7 These are the X-ray near-edge absorption structure spectrum, X-ray absorption fine structure spectrum, and fitting curve of the iron-containing side of the double-film catalytic electrode in Example 3-1;

[0032] Figure 8 These are the X-ray near-edge absorption structure spectrum, X-ray absorption fine structure spectrum, and fitting curve of the nickel-containing side of the double-film catalytic electrode in Example 3-1;

[0033] Figure 9 The graph shows the test results of the catalytic degradation system for pollutants in Example 3-1, Comparative Examples 3-1, 3-2, and 3-3 for the degradation of propranolol (PRO) in wastewater.

[0034] Figure 10 The graph shows the test results of the catalytic degradation system for pollutants in Examples 3-1, 3-2, 3-3, and 3-4 for the degradation of propranolol (PRO) in wastewater.

[0035] Figure 11 The graph shows the test results of the catalytic degradation system for pollutants in Examples 3-1, 3-5, and 3-6 for the degradation of propranolol (PRO) in wastewater.

[0036] Figure 12 These are the Raman spectra of the double-film catalytic electrodes in Examples 3-1, 3-5, and 3-6;

[0037] Figure 13 These are test curves showing the degradation of different pollutants using the catalytic degradation systems in Example 3-1 and Comparative Example 3-4, respectively.

[0038] Figure 14 The test curves show the degradation of different pollutants using the catalytic degradation system in Example 3-1.

[0039] Figure 15 These are the electron paramagnetic resonance spectra of the double-sided membrane catalytic electrode in Example 3-1, the membrane catalytic electrode in Comparative Example 3-1, the membrane catalytic electrode in Comparative Example 3-2, and the membrane catalytic electrode with mixed iron and nickel single atoms in Comparative Example 3-4.

[0040] Figure 16 This is the in-situ Raman spectrum of the double-film catalytic electrode in Example 3-1;

[0041] Figure 17 This is a quantitative test graph showing the steady-state concentration of active species and the concentration of hydrogen peroxide in the double-film catalytic electrode of Example 3-1;

[0042] Figure 18This is a graph showing the free energy change of the double-film catalytic electrode in Example 3-1 during the degradation of chloramphenicol;

[0043] Figure 19 This is a test diagram of the periodic degradation of propranolol pollutants by the dual-film catalytic electrode in Example 3-1;

[0044] Figure 20 This is a diagram illustrating the effect of the dual-film catalytic electrode in Example 3-1 on treating secondary effluent from pharmaceutical wastewater.

[0045] Figure 21 This is a fluorescence spectrum of the wastewater after secondary effluent from pharmaceutical wastewater treated by the double-film catalytic electrode in Example 3-1. Detailed Implementation

[0046] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0047] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0048] In one aspect, the present invention provides a dual-film catalytic electrode. According to an embodiment of the invention, the dual-film catalytic electrode comprises carbon skeleton fibers having a first surface and a second surface disposed opposite to each other. The first surface is loaded with a first transition metal single atom, and the second surface is loaded with a second transition metal single atom. One of the first and second transition metal single atoms is used to induce the generation of oxidizing active species, and the other is used to induce the generation of reducing active species. Thus, the catalytically active component, the transition metal, exists in the form of single atoms, which can effectively improve the catalytic activity and efficiency of the dual-film catalytic electrode and enhance the uniformity of catalysis. The first and second transition metal single atoms in the dual-film catalytic electrode can respectively induce the generation of oxidizing and reducing active species, achieving redox synergy, thereby reducing the energy barrier of the reaction and improving the reaction efficiency. Moreover, the first and second transition metal single atoms are located on the two surfaces of the dual-film catalytic electrode, and the two different transition metal single atoms are spaced apart, i.e., spatially partitioned, which can effectively reduce quenching reactions between active species, thereby further contributing to improving the reaction efficiency. Therefore, applying the above-mentioned double-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Moreover, since the first and second transition metal single atoms can induce the generation of oxidative and reductive active species, respectively, the reaction sequence of pollutants on the two surfaces of the double-film catalytic electrode can be adjusted by changing the wastewater flow direction according to different types of new pollutants, thereby achieving adjustable oxidation-reduction and efficiently removing new pollutants from wastewater.

[0049] It should be noted that the aforementioned transition metal single atoms refer to transition metals that are individually dispersed atoms supported on the surface of carbon skeletal fibers, with no interaction between the metals, i.e., no chemical bonds. However, the aforementioned single atom does not refer to the metal in an elemental atomic state, but rather to the presence of chemical bonds between the aforementioned transition metal single atoms and nonmetals, such as the coordination between the aforementioned transition metal single atom and nitrogen atoms through chemical bonds.

[0050] Furthermore, the aforementioned "the reaction sequence of pollutants on the two surfaces of the double-film catalytic electrode can be adjusted by changing the direction of wastewater flow" refers to adjusting the flow direction of wastewater from the first surface to the second surface, or from the second surface to the first surface.

[0051] According to some embodiments of the present invention, the transition metal single atom includes at least one of iron, nickel, copper, cobalt, zinc, and manganese. Thus, transition metal single atoms capable of inducing different active species are respectively loaded on the two surfaces of the double-film catalytic electrode. In some specific embodiments, iron single atoms and nickel single atoms can be loaded on the two surfaces of the double-film catalytic electrode, respectively. The iron single atom sites can induce the generation of the oxidizing active species hydroxyl radical (·OH), and the nickel single atom sites can induce the generation of the reducing active species atomic hydrogen (H*).

[0052] According to some embodiments of the present invention, the ratio of the first transition metal single atoms and the second transition metal single atoms respectively loaded on the two surfaces of the double-film catalytic electrode can be set according to the specific types of metals loaded. In some embodiments, the molar ratio of nickel single atoms to iron single atoms can be 1 / 20 to 1 / 5, such as 1 / 20, 1 / 15, 1 / 10, 3 / 20, 1 / 5, etc.

[0053] In some embodiments, the coordinating atoms coordinated with the transition metal include at least one of nitrogen, phosphorus, sulfur, and oxygen, and the number of coordinating atoms coordinated with a single transition metal atom is 1 to 6. In some specific embodiments, in the iron single-atom catalyst, the number of nitrogen atoms coordinated with iron is 6, and its main active site is of the Fe-N6 configuration; in the nickel single-atom catalyst, the number of nitrogen atoms coordinated with nickel is 4, and its main active site is of the Ni-N4 configuration.

[0054] According to some embodiments of the present invention, the oxidizing reactive species include one or more of hydroxyl radicals, sulfate radicals, or singlet oxygen, and the reducing reactive species include one or two of atomic hydrogen and hydrated electrons. This facilitates the deep degradation of novel pollutants such as propranolol (PRO), chloramphenicol (CAP), carbamazepine (CBZ), crotamethrin (CRO), antipyrine (ATP), p-chlorophenol (pCP), diclofenac (DCF), and ciprofloxacin (CIP), as well as recalcitrant organic wastewater (such as pharmaceutical wastewater, medical wastewater, landfill leachate, coal chemical wastewater, papermaking wastewater, and dyeing and printing wastewater).

[0055] In another aspect, the present invention provides a method for preparing the aforementioned dual-film catalytic electrode. According to an embodiment of the present invention, the method for preparing the dual-film catalytic electrode includes:

[0056] S100: The first spinning solution is obtained by uniformly mixing the first polymer, the first transition metal single-atom precursor, and the first organic solvent.

[0057] S200: The second spinning solution is obtained by uniformly mixing the second polymer, the second transition metal single-atom precursor, and the second organic solvent.

[0058] According to some embodiments of the present invention, the first polymer and the second polymer can be polymers such as polyacrylonitrile, polyvinylpyrrolidone, polyvinyl alcohol, polyester, and polyamide, respectively. There are no particular limitations on the molecular weight of the different polymers; those skilled in the art can determine this based on their experience. In some specific embodiments, the polymer is polyacrylonitrile with a molecular weight Mw = 150,000.

[0059] According to some embodiments of the present invention, the first organic solvent and the second organic solvent may be one or more of N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol or acetone, respectively.

[0060] According to some embodiments of the present invention, the first transition metal single-atom precursor comprises at least one of a metal-organic framework compound (MOF) containing a first transition metal, a phthalocyanine salt containing a first transition metal, or a mixture of a transition metal salt containing a first transition metal and a first organic compound. According to some embodiments of the present invention, the second transition metal single-atom precursor comprises at least one of a metal-organic framework compound (MOF) containing a second transition metal, a phthalocyanine salt containing a second transition metal, or a mixture of a transition metal salt containing a second transition metal and a second organic compound.

[0061] In some specific embodiments of the present invention, the aforementioned metal-organic framework compounds (MOFs) can be ZIF8 (zeolite imidazole ester framework structure material); phthalocyanine salts can be iron phthalocyanine, nickel phthalocyanine, copper phthalocyanine, cobalt phthalocyanine, zinc phthalocyanine, manganese phthalocyanine, etc.; transition metal salts can be iron acetylacetonate, nickel acetylacetonate, copper acetylacetonate, cobalt acetylacetonate, zinc acetylacetonate, manganese acetylacetonate, etc.; the first organic compound and the second organic compound can be phenanthroline (e.g., 1,10-phenanthroline), dopamine, etc., respectively. When metal-organic framework compounds are used as precursors, the prepared double-film catalytic electrode exhibits superior mechanical strength, and the membrane is less prone to rupture after degradation, resulting in a longer service life.

[0062] According to some embodiments of the present invention, the mass ratio of the first polymer to the first transition metal single-atom precursor is 1:0.01 to 1:3, such as 1:0.01, 1:0.05, 1:0.1, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.8, 1:3, etc.; according to some embodiments of the present invention, the mass ratio of the second polymer to the second transition metal single-atom precursor is 1:0.01 to 1:3, such as 1:0.01, 1:0.05, 1:0.1, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.8, 1:3, etc. This facilitates the loading of an appropriate amount of transition metal single atoms.

[0063] According to some embodiments of the present invention, the first spinning solution is prepared by method A, method B or method C:

[0064] The method for preparing the first spinning solution by method A includes: dissolving zinc nitrate and a first transition metal salt in a solvent, then adding 2-methylimidazole solution to the mixture to obtain a mixed solution; and obtaining a metal-organic framework compound containing the first transition metal by stirring, separating and drying the mixed solution; and uniformly mixing the metal-organic framework compound containing the first transition metal, the first polymer and the first organic solvent to obtain the first spinning solution.

[0065] In some embodiments, in method A described above, the first transition metal salt includes at least one of nitrates and acetylacetone salts, such as nickel nitrate, ferric nitrate, nickel acetylacetone, and ferric acetylacetone. In some embodiments, the solvent may be an organic solvent such as methanol or ethanol.

[0066] In other embodiments, the ratio of the first transition metal salt to the solvent is (0.05–5) mmol:100 mL, for example, ratios of 0.05 mmol:100 mL, 0.1 mmol:100 mL, 0.5 mmol:100 mL, 0.75 mmol:100 mL, 1 mmol:100 mL, 1.5 mmol:100 mL, 2.5 mmol:100 mL, 3.5 mmol:100 mL, 4.5 mmol:100 mL, 5 mmol:100 mL, etc. This facilitates the loading of appropriate amounts of transition metal single atoms into the double-film catalytic electrode.

[0067] In some other embodiments, the amount of the metal-organic framework compound added to the first spinning solution is 0.08–0.12 g / mL of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.08–0.12 g of the metal-organic framework compound; the amount of the first polymer added is 0.08–0.12 g / mL of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.08–0.12 g of the first polymer. This facilitates loading an appropriate amount of the first transition metal single atom into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0068] In some specific embodiments, taking iron as the first transition metal as an example, the preparation method of the first spinning solution includes: dissolving 10 mmol of zinc nitrate hexahydrate and 1-10 mmol (preferably 4-6 mmol of ferric acetylacetonate in some embodiments) in 100 mL of methanol, then adding 100 mL of methanol containing 80 mmol of 2-methylimidazole, and after stirring, standing, centrifugation, washing, and drying, obtaining an iron-containing metal-organic framework compound powder (abbreviated as Fe@ZIF8); then uniformly mixing 1 g of the metal-organic framework compound containing the first transition metal, 1 g of polyacrylonitrile (Mw = 150000) prepared above with 10 mL of N,N-dimethylformamide to obtain the first spinning solution.

[0069] The method for preparing the first spinning solution by method B includes: uniformly mixing a phthalocyanine salt containing a first transition metal, a first polymer, and a first organic solvent to obtain the first spinning solution.

[0070] In some embodiments, in method B above, the amount of phthalocyanine salt added to the first spinning solution is 0.01 to 0.2 mmol / mL (e.g., 0.01 mmol / mL, 0.02 mmol / mL, 0.03 mmol / mL, 0.04 mmol / mL, 0.05 mmol / mL, 0.06 mmol / mL, 0.07 mmol / mL, 0.08 mmol / mL, 0.09 mmol / mL, 0.1 mmol / mL, 0.12 mmol / mL, 0.15 mmol / mL, 0.18 mmol / mL, 0.2 mmol / mL, etc.) of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.01 to 0.2 mmol of phthalocyanine salt added; the amount of the first polymer added is 0.08 to 0.12 g / mL of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.08 to 0.12 g of the first polymer added. This facilitates the loading of an appropriate amount of first transition metal single atoms into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0071] In some specific embodiments, taking iron as the first transition metal, the preparation method of the first spinning solution includes: mixing 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), and 0.1–2 mmol of phthalocyanine iron to obtain the first spinning solution.

[0072] The method for preparing the first spinning solution by method C includes: uniformly mixing a first transition metal salt, a first organic compound, a first polymer, and a first organic solvent to obtain the first spinning solution, wherein the first organic compound includes at least one of phenanthroline and dopamine.

[0073] In some embodiments, in method C described above, the first transition metal salt includes at least one of nitrate and acetylacetone.

[0074] In some embodiments, the amount of the first transition metal salt added to the first spinning solution is 0.01 to 0.1 mmol / mL (e.g., 0.01 mmol / mL, 0.02 mmol / mL, 0.03 mmol / mL, 0.04 mmol / mL, 0.05 mmol / mL, 0.06 mmol / mL, 0.07 mmol / mL, 0.08 mmol / mL, 0.09 mmol / mL, 0.1 mmol / mL, etc.) of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.01 to 0.1 mmol of the first transition metal salt; the molar ratio of the first organic compound to the first transition metal salt is 4:1 to 8:1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, etc.; the amount of the first polymer added is 0.08 to 0.12 g / mL of the first organic solvent, that is, 1 mL of the first organic solvent corresponds to 0.08 to 0.12 g of the first polymer. This facilitates the loading of an appropriate amount of first transition metal single atoms into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0075] In some specific embodiments, taking iron as the first transition metal, the preparation method of the first spinning solution includes: uniformly mixing 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), 0.1-1 mmol of ferric acetylacetone and 1,10-phenanthroline to obtain the first spinning solution.

[0076] According to some embodiments of the present invention, the second spinning solution is prepared by method D, method E or method F:

[0077] The method for preparing the second spinning solution by method D includes: dissolving zinc nitrate and a second transition metal salt in a solvent, then adding a 2-methylimidazole solution to the mixture, and obtaining the metal-organic framework compound containing the second transition metal by stirring, separating, and drying; uniformly mixing the metal-organic framework compound containing the second transition metal, the second polymer, and the second organic solvent to obtain the second spinning solution.

[0078] In some embodiments, in method D described above, the second transition metal salt includes at least one of nitrates and acetylacetonates, such as nickel nitrate, ferric nitrate, nickel acetylacetonate, and ferric acetylacetonate. In some embodiments, the solvent may be an organic solvent such as methanol or ethanol.

[0079] In other embodiments, the ratio of the second transition metal salt to the solvent is (0.05–5) mmol:100 mL, for example, the ratio of the first transition metal salt to the solvent is 0.05 mmol:100 mL, 0.1 mmol:100 mL, 0.5 mmol:100 mL, 0.75 mmol:100 mL, 1 mmol:100 mL, 1.5 mmol:100 mL, 2.5 mmol:100 mL, 3.5 mmol:100 mL, 4.5 mmol:100 mL, 5 mmol:100 mL, etc. This facilitates the loading of appropriate amounts of transition metal single atoms into the double-film catalytic electrode.

[0080] In some other embodiments, the amount of the metal-organic framework compound added to the second spinning solution is 0.08–0.12 g / mL of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.08–0.12 g of the metal-organic framework compound; the amount of the second polymer added is 0.08–0.12 g / mL of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.08–0.12 g of the second polymer. This facilitates loading an appropriate amount of the first transition metal single atom into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0081] In some specific embodiments, taking nickel as the second transition metal as an example, the preparation method of the first spinning solution includes: dissolving 10 mmol of zinc nitrate hexahydrate and 0.1-2 mmol (preferably 0.5-0.75 mmol of ferric acetylacetone) of nickel nitrate hexahydrate in 100 mL of methanol, then adding 100 mL of methanol containing 80 mmol of 2-methylimidazole, and after stirring, standing, centrifugation, washing, and drying, obtaining a nickel-containing metal-organic framework compound powder (which can be abbreviated as Ni@ZIF8); then uniformly mixing 1 g of the metal-organic framework compound containing the second transition metal, 1 g of polyacrylonitrile (Mw = 150000) prepared above with 10 mL of N,N-dimethylformamide to obtain the second spinning solution.

[0082] The method for preparing the second spinning solution by method E includes: uniformly mixing the phthalocyanine salt containing the second transition metal, the second polymer, and the second organic solvent to obtain the second spinning solution.

[0083] In some embodiments, in method E above, the amount of phthalocyanine salt added to the second spinning solution is 0.01–0.2 mmol / mL (e.g., 0.01 mmol / mL, 0.02 mmol / mL, 0.03 mmol / mL, 0.04 mmol / mL, 0.05 mmol / mL, 0.06 mmol / mL, 0.07 mmol / mL, 0.08 mmol / mL, 0.09 mmol / mL, 0.1 mmol / mL, 0.12 mmol / mL, 0.15 mmol / mL, 0.18 mmol / mL, 0.2 mmol / mL, etc.) of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.01–0.2 mmol of phthalocyanine salt added; the amount of the second polymer added is 0.08–0.12 g / mL of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.08–0.12 g of the second polymer added. This facilitates the loading of an appropriate amount of second transition metal single atoms into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0084] In some specific embodiments, taking nickel as the second transition metal as an example, the preparation method of the second spinning solution includes: mixing 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), and 0.1–2 mmol of nickel phthalocyanine to obtain the second spinning solution.

[0085] The method for preparing the second spinning solution by method F includes: uniformly mixing a second transition metal salt, a second organic compound, a second polymer, and a second organic solvent to obtain the second spinning solution, wherein the second organic compound includes at least one of phenanthroline and dopamine.

[0086] In some embodiments, in method C described above, the second transition metal salt includes at least one of nitrate and acetylacetone.

[0087] In some embodiments, the amount of the second transition metal salt added to the second spinning solution is 0.01–0.1 mmol / mL (e.g., 0.01 mmol / mL, 0.02 mmol / mL, 0.03 mmol / mL, 0.04 mmol / mL, 0.05 mmol / mL, 0.06 mmol / mL, 0.07 mmol / mL, 0.08 mmol / mL, 0.09 mmol / mL, 0.1 mmol / mL, etc.) of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.01–0.1 mmol of the second transition metal salt; the molar ratio of the second organic compound to the second transition metal salt is 4:1–8:1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, etc.; the amount of the second polymer added is 0.08–0.12 g / mL of the second organic solvent, that is, 1 mL of the second organic solvent corresponds to 0.08–0.12 g of the second polymer. This facilitates the loading of an appropriate amount of second transition metal single atoms into the double-film catalytic electrode, thereby helping to improve the catalytic activity of the double-film catalytic electrode.

[0088] In some specific embodiments, taking nickel as the second transition metal as an example, the preparation method of the second spinning solution includes: uniformly mixing 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), 0.1-1 mmol of nickel acetylacetonate and 1,10-phenanthroline to obtain the second spinning solution.

[0089] According to some embodiments of the present invention, the preparation methods of the first spinning solution and the second spinning solution are basically the same, both of which can select three different transition metal single-atom precursors. The first spinning solution and the second spinning solution can use the same transition metal single-atom precursor or different transition metal single-atom precursors, which can be flexibly selected by those skilled in the art according to actual needs. For example, if the first spinning solution can be prepared by method A, then the second spinning solution can be prepared by method D, method E, or method F. That is to say, there is no specific correspondence between the preparation methods used for the first spinning solution and the second spinning solution, and they can be prepared independently of each other.

[0090] S300: First, electrospinning is performed using the first spinning solution for a period of time, then the second spinning solution is replaced to continue the second electrospinning to obtain a double-film intermediate.

[0091] In some embodiments of the present invention, the spinning voltage in the first electrospinning and the second electrospinning is 15–25 kV, and the nozzle distance is 10–18 cm. This is beneficial for obtaining finer spun fibers, which helps to increase the loading area of ​​transition metal single atoms and improve catalytic activity.

[0092] S400: Pre-oxidize the intermediate of the double-sided film to obtain a pre-oxidized double-sided film.

[0093] According to some embodiments of the present invention, the pre-oxidation treatment conditions include a temperature of 240–300°C and a time of 0.5–3 hours. Thus, through the pre-oxidation process, the first and second polymers undergo reactions such as cyclization, dehydrogenation, oxidation, and cross-linking, preventing the fibers from melting and burning during subsequent carbonization at higher temperatures, thereby increasing the applicable carbonization temperature. In some specific embodiments, the pre-oxidation treatment temperature can be 260–280°C, and the time can be 2 hours. Furthermore, this pre-oxidation treatment can be carried out in a muffle furnace.

[0094] S500: Carbonize the pre-oxidized double-sided film to obtain a double-sided film catalytic electrode.

[0095] According to some embodiments of the present invention, the carbonization treatment conditions include a temperature of 600–1400°C and a time of 0.5–3 hours. This effectively achieves the carbonization of the polymer, yielding carbon skeleton fibers, and converting the loaded transition metal into metal single atoms. In some specific embodiments, the carbonization treatment temperature is 900–1100°C, and the time is 1 hour.

[0096] According to embodiments of the present invention, in the double-film catalytic electrode prepared by the above method, the first transition metal single atom and the second transition metal single atom can respectively induce the generation of oxidative and reductive active species, achieving redox synergy, thereby reducing the energy barrier of the reaction and improving the reaction efficiency. Furthermore, the first and second transition metal single atoms are located on the two surfaces of the double-film catalytic electrode, with a certain distance between the two different transition metal single atoms, which can effectively reduce quenching reactions between active species, further contributing to improved reaction efficiency. Therefore, applying the above-mentioned double-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Moreover, since the first and second transition metal single atoms can respectively induce the generation of oxidative and reductive active species, the order in which wastewater flows to the two surfaces of the double-film catalytic electrode can be adjusted according to different types of new pollutants, better in-situ redox synergy can be achieved, thereby efficiently removing new pollutants from the wastewater.

[0097] In another aspect, the present invention provides an application of the aforementioned dual-film catalytic electrode in the degradation of pollutants. Thus, applying the above-mentioned dual-film catalytic electrode to wastewater treatment containing new pollutants can effectively remove various types of new pollutants from the wastewater. Since the first and second transition metal single atoms can respectively induce the generation of oxidative and reductive species, the order in which wastewater flows to the two surfaces of the dual-film catalytic electrode can be adjusted according to different types of new pollutants, thereby achieving better in-situ synergistic oxidation-reduction and efficiently removing new pollutants from the wastewater.

[0098] According to some embodiments of the present invention, the pollutant can be a novel pollutant such as propranolol (PRO), chloramphenicol (CAP), carbamazepine (CBZ), crotamethon (CRO), antipyrine (ATP), p-chlorophenol (pCP), diclofenac (DCF), ciprofloxacin (CIP), or other recalcitrant organic wastewater (such as pharmaceutical wastewater, medical wastewater, landfill leachate, coal chemical wastewater, papermaking wastewater, and printing and dyeing wastewater).

[0099] In another aspect, the present invention provides a system for catalytically degrading pollutants. According to embodiments of the present invention, the system for catalytically degrading pollutants includes: an anode; and a cathode, wherein the cathode is the aforementioned double-film catalytic electrode, or the double-film catalytic electrode prepared by the aforementioned method. Thus, this system can effectively remove various new pollutants from water.

[0100] According to some embodiments of the present invention, the anode may be an inert titanium mesh.

[0101] According to some embodiments of the present invention, the catalytic degradation system for pollutants may further include a current collector layer, and more specifically, a stainless steel mesh may be used as the current collector layer. In some embodiments, in the catalytic degradation system for pollutants, an annular titanium sheet is connected to a power source, and the cathode and anode are separated by a plastic mesh to prevent short circuits.

[0102] In some specific embodiments, the catalytic degradation system for pollutants includes an inlet chamber, a double-film catalytic electrode (i.e., cathode), a current collector layer, a plastic mesh, an anode, and an outlet chamber arranged in sequence.

[0103] In some embodiments, there are no special requirements for the effective filtration area of ​​the cathode and anode in the catalytic degradation pollutant system, and those skilled in the art can design flexibly according to actual usage requirements.

[0104] According to some embodiments of the present invention, during pollutant degradation, the voltage between the anode and cathode is 0.5–5V at normal temperature and pressure, and the membrane flux of the wastewater is 50–2000 L / m³. -2 h -1 .

[0105] Example

[0106] Example 1-1

[0107] Methods for preparing double-film catalytic electrodes include:

[0108] Preparation of the first spinning solution: 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), 0.5 mmol of ferric acetylacetone, and 3 mmol of 1,10-phenanthroline (the molar ratio of 1,10-phenanthroline to ferric acetylacetone is 6:1) are mixed uniformly to obtain the first spinning solution.

[0109] Preparation of the second spinning solution: 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000), 0.5 mmol of nickel acetylacetone, and 3 mmol of 1,10-phenanthroline (the molar ratio of 1,10-phenanthroline to nickel acetylacetone is 6:1) are mixed uniformly to obtain the second spinning solution.

[0110] First, electrospinning is performed for a period of time using the first spinning solution. Then, the second spinning solution is replaced to continue the second electrospinning to obtain a double-film intermediate. The spinning voltage is 21kV and the nozzle distance is 15cm.

[0111] The intermediate of the double-sided film was pre-oxidized at 280℃ for 1 hour to obtain the pre-oxidized double-sided film.

[0112] The pre-oxidized double-sided film was carbonized at 1000℃ for 1 h to obtain a double-sided film catalytic electrode (Janus Fe-Ni SA@CF) loaded with iron and nickel single atoms, respectively. Figure 1 The corresponding test curve for Janus Fe-Ni SA@CF (0.5 mmol) is shown in the figure. Figure 2 The corresponding test curve is Janus Fe-Ni SA@CF (280℃).

[0113] In the catalytic degradation system for pollutants, an inert titanium mesh is used as the anode, and the aforementioned prepared double-film catalytic electrode, Janus Fe-Ni SA@CF, is used as the cathode. The effective filtration area of ​​both the anode and cathode is 7 cm². 2 A stainless steel mesh is used as the current collector layer, which is connected to the power supply through a ring-shaped titanium sheet. The anode and cathode are separated by a plastic mesh with a thickness of 0.5 mm to avoid short circuits.

[0114] Examples 1-2

[0115] The method for preparing the dual-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Examples 1-1 is basically the same, except that: in the preparation of the first spinning solution, the amount of iron acetylacetone is 0.4 mmol; and in the preparation of the second spinning solution, the amount of nickel acetylacetone is 0.4 mmol. Figure 1 The corresponding test curve is Janus Fe-Ni SA@CF (0.4 mmol).

[0116] Examples 1-3

[0117] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Examples 1-1 is basically the same, except that: in the preparation of the first spinning solution, the amount of iron acetylacetone is 0.3 mmol; in the preparation of the second spinning solution, the amount of nickel acetylacetone is 0.3 mmol. Figure 1 The corresponding test curve is Janus Fe-Ni SA@CF (0.3 mmol).

[0118] Examples 1-4

[0119] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Examples 1-1 is basically the same, except that the pre-oxidation treatment temperature is 250℃. Figure 2 The corresponding test curve is Janus Fe-Ni SA@CF (250℃).

[0120] Examples 1-5

[0121] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Examples 1-1 is basically the same, except that the pre-oxidation treatment temperature is 240℃. Figure 2 The corresponding test curve is Janus Fe-Ni SA@CF (240℃).

[0122] The catalytic degradation systems for pollutants described in Examples 1-1, 1-2, 1-3, 1-4, and 1-5 were used to degrade propranolol (PRO) in wastewater, respectively. The test results can be found in the respective examples. Figure 1 and Figure 2 The initial concentration of propranolol in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1The wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms.

[0123] Depend on Figure 1 It can be seen that when the amount of acetylacetone salt in the first and second spinning solutions is 0.5 mmol, the removal rate of propranolol can reach 86% within 20 minutes. However, after the degradation is completed, the mechanical properties of the double-film catalytic electrode decrease significantly and it often breaks.

[0124] Depend on Figure 2 It can be seen that when the pre-oxidation temperature is reduced from 280℃ to 250℃, only a few cracks appear in the negative electrode film. Figure 3 Therefore, it can be seen that lowering the pre-oxidation temperature can improve the mechanical strength of the membrane; however, the degradation effect of propranolol decreases rapidly after the pre-oxidation temperature is lowered. Figure 2 This is mainly because at lower pre-oxidation temperatures (250°C and below), pre-oxidation cannot proceed sufficiently, and the amorphization transformation and aromatization of carbon cannot be completed.

[0125] Example 2-1

[0126] Methods for preparing double-film catalytic electrodes include:

[0127] Preparation of the first spinning solution: 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000) and 0.5 mmol of phthalocyanine iron were mixed evenly to obtain the first spinning solution.

[0128] Preparation of the second spinning solution: 10 mL of N,N-dimethylformamide, 1 g of polyacrylonitrile (Mw = 150000) and 0.5 mmol of phthalocyanine iron were mixed evenly to obtain the second spinning solution.

[0129] First, electrospinning is performed for a period of time using the first spinning solution. Then, the second spinning solution is replaced to continue the second electrospinning to obtain a double-film intermediate. The spinning voltage is 21kV and the nozzle distance is 15cm.

[0130] The intermediate of the double-sided film was pre-oxidized at 280℃ for 1 hour to obtain the pre-oxidized double-sided film.

[0131] The pre-oxidized double-sided film was carbonized at 1000℃ for 1 h to obtain a double-sided film catalytic electrode (Janus Fe-Ni SA@CF) loaded with iron and nickel single atoms, respectively. Figure 4 The corresponding test curve is Janus Fe-Ni SA@CF (0.5 mmol).

[0132] The setup requirements for the catalytic degradation pollutant system are the same as in Example 1-1.

[0133] Example 2-2

[0134] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 2-1 is basically the same, except that: in the preparation of the first spinning solution, the amount of iron phthalocyanine is 0.75 mmol; in the preparation of the second spinning solution, the amount of nickel phthalocyanine is 0.75 mmol. Figure 4 The corresponding test curve is Janus Fe-Ni SA@CF (0.75 mmol).

[0135] Example 2-3

[0136] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 2-1 is basically the same, except that: in the preparation of the first spinning solution, the amount of iron phthalocyanine is 1 mmol; in the preparation of the second spinning solution, the amount of nickel phthalocyanine is 1 mmol. Figure 4 The corresponding test curve is Janus Fe-Ni SA@CF (1 mmol)).

[0137] Comparative Example 2-1

[0138] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 2-1 is basically the same, except that: in the preparation of the first spinning solution, iron phthalocyanine is replaced with iron acetylacetonate; and in the preparation of the second spinning solution, nickel phthalocyanine is replaced with nickel acetylacetonate. Figure 4 The corresponding test curve is Janus Fe-Ni@CF (0.5 mmol).

[0139] The catalytic degradation systems for pollutants in Examples 2-1, 2-2, 2-3, and Comparative Example 2-1 were used to degrade propranolol (PRO) in wastewater. The test results can be found in the respective examples. Figure 4 The initial concentration of propranolol in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3, and the membrane flux was 680 L / m³. -2 h -1 The wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms.

[0140] Depend on Figure 4It is evident that the degradation efficiency of propranolol by the Janus Fe-Ni SA@CF cathode membrane decreases rapidly with increasing phthalocyanine salt doping concentration, and its mechanical properties also decrease accordingly. Furthermore, compared to a non-single-atom catalytic electrode membrane (Janus Fe-Ni@CF) with the same metal doping concentration, the single-atom-supported double-sided membrane catalytic electrode in this example exhibits significantly superior catalytic performance, achieving a 79% removal rate of propranolol within 20 minutes.

[0141] Example 3-1

[0142] Methods for preparing double-film catalytic electrodes include:

[0143] Preparation of the first spinning solution: 10 mmol zinc nitrate hexahydrate and 5 mmol iron acetylacetonate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, iron-containing metal-organic framework compound powder (Fe@ZIF8) was obtained. Then, 1 g of the metal-organic framework compound containing the first transition metal prepared above, 1 g of polyacrylonitrile (Mw = 150000) and 10 mL of N,N-dimethylformamide were mixed evenly to obtain the first spinning solution.

[0144] Preparation of the second spinning solution: 10 mmol zinc nitrate hexahydrate and 0.5 mmol nickel nitrate hexahydrate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, a nickel-containing metal-organic framework compound powder (Ni@ZIF8) was obtained. Then, 1 g of the metal-organic framework compound containing the second transition metal prepared above, 1 g of polyacrylonitrile (Mw = 150000) and 10 mL of N,N-dimethylformamide were mixed evenly to obtain the second spinning solution.

[0145] First, electrospinning is performed for a period of time using the first spinning solution. Then, the second spinning solution is replaced to continue the second electrospinning to obtain a double-film intermediate. The spinning voltage is 21kV and the nozzle distance is 15cm.

[0146] The intermediate of the double-sided film was pre-oxidized at 280℃ for 2 hours to obtain the pre-oxidized double-sided film.

[0147] The pre-oxidized double-sided film was carbonized at 1000℃ for 1 h to obtain a double-sided film catalytic electrode (Janus Fe-Ni SA@CF) loaded with iron and nickel single atoms respectively, wherein the molar ratio of nickel to iron single atoms was 1 / 10 (in Figure 10 The curve corresponding to the test results in Janus Fe-Ni 1 / 10 SA@CF).

[0148] The setup requirements for the catalytic degradation pollutant system are the same as in Example 1-1.

[0149] The tensile stress of the double-film catalytic electrode (Janus Fe-Ni SA@CF) obtained in this embodiment was tested, and the test results are as follows. Figure 5 As shown, the maximum tensile stress of the dual-film catalytic electrode (Janus Fe-Ni SA@CF) is 4.60 MPa, which is 4.3 times that of pure carbon fiber CF. This demonstrates that the dual-film catalytic electrode of the present invention has excellent mechanical properties.

[0150] Electron microscopy scanning tests were performed on both sides of the dual-film catalytic electrode (Janus Fe-Ni SA@CF) obtained in this embodiment, as follows: Figure 6a As shown ( Figure 6a The images on the left, middle, and right sides are scanning electron microscope (SEM), transmission electron microscope (TEM), and high-angle annular dark-field scanning TEM (SEM) images, respectively. TEM images show the iron-containing metal-organic framework (MOF) powder (Fe@ZIF8) and nickel-containing MOF powder (Ni@ZIF8) obtained during the above preparation process. Figure 6b ( Figure 6b The left image in the middle section is a scanning electron microscope (SEM) image of an iron-containing metal-organic framework compound, and the right image is a SEM image of a nickel-containing metal-organic framework compound. Figure 6a and 6b It is evident that the iron- and nickel-containing metal-organic framework compounds all exhibit a dodecahedral shape, which is maintained even after being incorporated into both sides of the carbon fiber membrane and subjected to pyrolysis, and the carbon fibers are continuous and uniform. From the transmission electron microscopy (TEM) images and high-angle annular dark-field scanning TEM images, it can be seen that carbon, nitrogen, oxygen, and iron / nickel elements are all uniformly distributed, with no obvious nanoparticles. Furthermore, the high-angle annular dark-field scanning TEM images show that iron and nickel are dispersed in the carbon fiber membrane in the form of single atoms.

[0151] X-ray near-edge absorption spectra of the iron-containing and nickel-containing sides of the double-film catalytic electrode (Janus Fe-Ni SA@CF) obtained in this embodiment were obtained (e.g., Figure 7 (a) and Figure 8 (a) in the image), X-ray absorption fine structure spectrum (e.g. Figure 7 (b) and Figure 8 (b) and fitting curve testing (e.g.) Figure 7 (c) and Figure 8 (c) in the middle. Figure 7 and Figure 8As can be seen, the valence states of Fe and Ni are both close to +2. X-ray absorption fine structure spectra show that only Fe-N and Ni-N peaks were observed in the single-atom catalysts of iron and nickel, further confirming that iron and nickel are in an atomically dispersed state. Further curve fitting analysis revealed that in the iron single-atom catalyst, the number of nitrogen atoms coordinated with iron is 6, therefore its main active site is the Fe-N6 configuration; in the nickel single-atom catalyst, the number of nitrogen atoms coordinated with nickel is 4, therefore its main active site is the Ni-N4 configuration.

[0152] Comparative Example 3-1

[0153] Methods for preparing double-film catalytic electrodes include:

[0154] Preparation of the first spinning solution: 10 mmol zinc nitrate hexahydrate and 5 mmol iron acetylacetonate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, iron-containing metal-organic framework compound powder (Fe@ZIF8) was obtained. Then, 1 g of the metal-organic framework compound containing the first transition metal prepared above, 1 g of polyacrylonitrile (Mw = 150000) and 10 mL of N,N-dimethylformamide were mixed evenly to obtain the first spinning solution.

[0155] Electrospinning was performed using the first spinning solution for a period of time to obtain a catalytic membrane intermediate, wherein the spinning voltage was 21kV and the nozzle distance was 15cm.

[0156] The catalytic membrane intermediate was pre-oxidized at 280℃ for 2 hours to obtain a pre-oxidized membrane.

[0157] The pre-oxidized membrane was carbonized at 1000℃ for 1 h to obtain a membrane catalytic electrode (FeSA@CF) loaded with only iron single atoms.

[0158] The setup requirements for the catalytic degradation pollutant system are the same as in Example 3-1.

[0159] Comparative Example 3-2

[0160] Methods for preparing double-film catalytic electrodes include:

[0161] Preparation of the second spinning solution: 10 mmol zinc nitrate hexahydrate and 0.5 mmol nickel nitrate hexahydrate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, a nickel-containing metal-organic framework compound powder (Ni@ZIF8) was obtained. Then, 1 g of the metal-organic framework compound containing the second transition metal prepared above, 1 g of polyacrylonitrile (Mw = 150000) and 10 mL of N,N-dimethylformamide were mixed evenly to obtain the second spinning solution.

[0162] Electrospinning was continued using the second spinning solution to obtain the catalytic membrane intermediate. The spinning voltage was 21 kV and the nozzle distance was 15 cm.

[0163] The catalytic membrane intermediate was pre-oxidized at 280℃ for 2 hours to obtain a pre-oxidized membrane.

[0164] The pre-oxidized film was carbonized at 1000℃ for 1 h to obtain a membrane catalytic electrode (NiSA@CF) loaded with only nickel single atoms.

[0165] The setup requirements for the catalytic degradation pollutant system are the same as in Example 3-1.

[0166] Comparative Example 3-3

[0167] The setup requirements for the catalytic degradation pollutant system are the same as in Example 3-1, except that a simple carbon fiber membrane (CF) is used as the cathode of the system.

[0168] The catalytic degradation systems for pollutants in Example 3-1, Comparative Examples 3-1, 3-2, and 3-3 were used to degrade propranolol (PRO) in wastewater. The test results can be found in the respective examples. Figure 9 The initial concentration of propranolol in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1 In Example 3-1, the wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms.

[0169] Depend on Figure 9 It is evident that the Janus Fe-Ni SA@CF membrane cathode exhibits superior electrochemical catalytic properties, achieving complete removal of propranolol within 15 minutes, with a first-order reaction kinetic constant (k = 0.315 min). -1 It is 1.7 to 6.3 times that of the other three types of membrane electrodes. Figure 9This indicates that the Janus Fe-Ni SA@CF membrane cathode can efficiently remove propranolol.

[0170] Example 3-2

[0171] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 3-1 is basically the same, except that: in the preparation of the second spinning solution, the amount of nickel nitrate hexahydrate used is 0.25 mmol; in the prepared double-film catalytic electrode (Janus Fe-Ni SA@CF), the molar ratio of nickel to iron single atoms is 1 / 20 (in... Figure 10 The curve corresponding to the test results in Janus Fe-Ni 1 / 20 SA@CF).

[0172] Example 3-3

[0173] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 3-1 is basically the same, except that: in the preparation of the second spinning solution, the amount of nickel nitrate hexahydrate used is 0.75 mmol; in the prepared double-film catalytic electrode (Janus Fe-Ni SA@CF), the molar ratio of nickel to iron single atoms is 3 / 20 (in...). Figure 10 The curve corresponding to the test results in Janus Fe-Ni 3 / 20 SA@CF).

[0174] Examples 3-4

[0175] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 3-1 is basically the same, except that: in the preparation of the second spinning solution, the amount of nickel nitrate hexahydrate used is 1 mmol; in the prepared double-film catalytic electrode (Janus Fe-Ni SA@CF), the molar ratio of nickel to iron single atoms is 1 / 5 (in... Figure 10 The curve corresponding to the test results in Janus Fe-Ni 1 / 5 SA@CF).

[0176] The catalytic degradation systems described in Examples 3-1, 3-2, 3-3, and 3-4 were used to degrade propranolol (PRO) in wastewater, respectively. The test results can be found in the respective examples. Figure 10 The initial concentration of propranolol in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1The wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms.

[0177] The results showed that the degradation effect first increased and then decreased with increasing nickel doping concentration, reaching its maximum when the nickel to iron molar ratio was 1 / 10 (refer to...). Figure 10 This is mainly because excessive nickel doping causes nickel single atoms to agglomerate into nanoparticles, thereby reducing catalytic efficiency.

[0178] Examples 3-5

[0179] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 3-1 is basically the same, except that the carbonization temperature is 900℃.

[0180] Examples 3-6

[0181] The method for preparing the double-film catalytic electrode Janus Fe-Ni SA@CF and the catalytic degradation system for pollutants in Example 3-1 is basically the same, except that the carbonization temperature is 1100℃.

[0182] The catalytic degradation systems for pollutants described in Examples 3-1, 3-5, and 3-6 were used to degrade propranolol (PRO) in wastewater, respectively. The test results can be found in the respective examples. Figure 11 The initial concentration of propranolol in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1 The wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms.

[0183] Depend on Figure 11 The test results show that the degradation effect increases with increasing carbonization temperature. When the carbonization temperature increases from 900℃ to 1000℃, the k value increases by 81%, while when it increases from 1000℃ to 1100℃, it only increases by 5%.

[0184] Raman spectroscopy was performed on the double-film catalytic electrodes in Examples 3-1, 3-5, and 3-6, and the test results are as follows: Figure 12 Raman spectroscopy showed that the carbon fibers exhibited the highest degree of graphitization at a carbonization temperature of 1000℃, which is beneficial for the catalytic reaction. Although conductivity increases monotonically with carbonization temperature, the increase has a negligible effect on improving the electrocatalytic effect when conductivity is high. Therefore, a carbonization temperature of 1000℃ is optimal.

[0185] Comparative Examples 3-4

[0186] Methods for preparing hybrid membrane catalytic electrodes include:

[0187] Preparation of Fe@ZIF8: 10 mmol zinc nitrate hexahydrate and 5 mmol iron acetylacetonate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, an iron-containing metal-organic framework compound powder (abbreviated as Fe@ZIF8) was obtained. Preparation of Ni@ZIF8: 10 mmol zinc nitrate hexahydrate and 0.5 mmol nickel nitrate hexahydrate were dissolved in 100 mL methanol, and then 100 mL methanol containing 80 mmol 2-methylimidazole was added. After stirring, standing, centrifugation, washing, and drying, a nickel-containing metal-organic framework compound powder (abbreviated as Ni@ZIF8) was obtained.

[0188] The above-prepared 1g iron-containing metal-organic framework compound, 1g nickel-containing metal-organic framework compound, 2g polyacrylonitrile (Mw=150000) and 20mL N,N-dimethylformamide were uniformly mixed to obtain a mixed spinning solution.

[0189] Electrospinning was continued using the mixed spinning solution to obtain a mixed film intermediate, wherein the spinning voltage was 21kV and the nozzle distance was 15cm;

[0190] The mixed membrane intermediate was pre-oxidized at 280℃ for 2 hours to obtain a pre-oxidized mixed membrane.

[0191] The pre-oxidized mixed membrane was carbonized at 1000℃ for 1 h to obtain a membrane catalytic electrode (Mixed Fe-Ni SA@CF) with mixed iron and nickel single atoms.

[0192] The setup requirements for the catalytic degradation pollutant system are the same as in Example 3-1.

[0193] The catalytic degradation systems described in Example 3-1 and Comparative Example 3-4 were used to degrade the first and second wastewaters, respectively. The pollutant in the first wastewater was propranolol (PRO), and the pollutant in the second wastewater was chloramphenicol (CAP). The test results can be found in [references to be inserted here]. Figure 13 The initial concentrations of propranolol and chloramphenicol in the wastewater before degradation were both 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1 In this study, two sets of tests were conducted on the double-film catalytic electrode in Example 3-1. One set of tests involved wastewater flowing from the surface loaded with iron single atoms to the surface loaded with nickel single atoms, i.e., the iron-containing side facing the inlet end (corresponding to...). Figure 13 (Janus Fe-Ni SA@CF curve); another set of tests showed that the wastewater flowed from the surface loaded with nickel single atoms to the surface loaded with iron single atoms, that is, the nickel-containing side faced the inlet (corresponding to...). Figure 13 (Janus Ni-Fe SA@CF curve).

[0194] Depend on Figure 13 The test results show that in the degradation tests of propranolol and chloramphenicol, the Janus Fe-Ni SA@CF membrane cathode exhibited a higher degradation effect than the Mixed Fe-Ni SA@CF membrane cathode. In the degradation of propranolol, when the iron-containing side of the Janus Fe-Ni SA@CF membrane cathode faced the inlet (k = 0.340 min), the degradation efficiency was significantly higher. -1 The degradation effect was better than that of the nickel-containing side-facing inlet end (Janus Ni-Fe SA@CF, k=0.267min). -1 Conversely, in the degradation of chloramphenicol (CAP), the nickel-containing side faces the inlet end (k = 0.355 min). -1 The degradation effect was better at the iron-containing side facing the inlet (k = 0.133 min). -1 ).

[0195] The catalytic degradation system for pollutants described in Example 3-1 was used to degrade wastewater containing different pollutants. The test results can be found in the respective examples. Figure 14 The initial concentration of pollutants in the wastewater before degradation was 5 mg / L, and the wastewater volume was 50 mL. During the 20-minute degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1 Furthermore, for each pollutant, the dual-film catalytic electrode in Example 3-1 underwent two sets of tests. One set of tests involved wastewater flowing from the surface loaded with iron single atoms to the surface loaded with nickel single atoms, i.e., the iron-containing side facing the inlet (corresponding to...). Figure 14 (Janus Fe-Ni SA@CF curve); another set of tests showed that the wastewater flowed from the surface loaded with nickel single atoms to the surface loaded with iron single atoms, that is, the nickel-containing side faced the inlet (corresponding to...). Figure 14 (Janus Ni-Fe SA@CF curve).

[0196] Depend on Figure 14The test results show that amide-based organic pollutants such as propranolol, carbamazepine (CBZ), crotamate (CRO), and antipyrine (ATP) are removed more quickly when the iron-containing side faces the inlet, with a k-value 1.5 to 2.5 times that of the nickel-containing side facing the inlet. Halogenated organic pollutants such as chloramphenicol, p-chlorophenol (pCP), diclofenac (DCF), and ciprofloxacin (CIP) all have larger k-values ​​(1.1 to 4.9 times) when the nickel-containing side faces the inlet. This demonstrates that different sequences of inlet and outlet directions are suitable for different types of new pollutants, and the dominant sequence is related to their characteristic chemical groups. Furthermore, under the corresponding dominant sequence, all eight model pollutants achieved removal rates of over 80% within 20 minutes, fully demonstrating the excellent electrocatalytic properties and broad adaptability of the Janus Fe-Ni SA@CF membrane cathode of this invention.

[0197] Electron paramagnetic resonance (EPR) analyses were performed on the dual surfaces of the bifacial catalytic electrode (Janus Fe-Ni SA@CF) in Example 3-1, the membrane catalytic electrode (Fe SA@CF) in Comparative Example 3-1, the membrane catalytic electrode (Ni SA@CF) in Comparative Example 3-2, and the membrane catalytic electrode (Mixed Fe-Ni SA@CF) with mixed iron and nickel single atoms in Comparative Example 3-4. Figure 15 As shown, hydroxyl radicals (·OH) and atomic hydrogen (H*) are the main active species in the double-film catalytic electrode (Janus Fe-Ni SA@CF). Iron single-atom sites primarily generate ·OH, while nickel single-atom sites primarily generate H*. The signals from both species are very weak in the MixedFe-Ni SA@CF film cathode. This is mainly because the iron and nickel single-atom sites are too close together, leading to mutual reaction and quenching consumption between the two species.

[0198] In-situ Raman spectroscopy was performed on both surfaces of the dual-film catalytic electrode (Janus Fe-Ni SA@CF) in Example 3-1, as follows: Figure 16 Therefore, it can be seen that the process of generating ·OH and H* is as follows: oxygen first undergoes a one-electron reduction at the iron single-atom site to become *OO. - This leads to the formation of *OOH, a key intermediate in the hydrogen peroxide production process; while water forms hydrated nickel at the nickel single-atom site, further proving that *H can be generated at the nickel single-atom site.

[0199] Furthermore, the active species on the dual surfaces of the double-film catalytic electrode (Janus Fe-Ni SA@CF) in Example 3-1 were quantitatively tested using probe experiments, such as... Figure 17 As shown. The steady-state concentration of ·OH generated by the mixed Fe-Ni SA@CF membrane cathode (5.7 × 10⁻⁶) -14 mol L -1 The concentration of hydrogen peroxide (·OH) was only 1 / 5 to 1 / 3 that of the Janus Fe-Ni SA@CF membrane cathode, further demonstrating that the close proximity of active sites leads to mutual quenching of active species. When the iron-containing side faces the inlet, the steady-state concentration of ·OH is 1.7 times that when the nickel-containing side faces the inlet, while the hydrogen peroxide concentration is even lower. This is because when the iron-containing side faces the inlet, the hydrogen peroxide generated on the iron-containing side can migrate with the water flow to the nickel-containing side and react with H*, resulting in more activation and the generation of ·OH.

[0200] The synergistic mechanism of ·OH and H* in pollutant degradation: The direct reaction between propranolol and H* is relatively weak. Its better degradation effect on the iron-containing side facing the influent end is attributed to the higher ·OH concentration. Chloramphenicol, on the other hand, can undergo dechlorination under the action of H*. On the nickel-containing side facing the influent end, the reaction sequence of dechlorination followed by hydroxylation is thermodynamically more advantageous than that of hydroxylation followed by dechlorination (e.g., ...). Figure 18 As shown in the diagram, chloramphenicol exhibits better degradation when the nickel-containing side faces the inlet water in sequence. Therefore, the underlying mechanism of the inlet water sequential strategy in this application is as follows: when the iron-containing side faces the inlet water, more ·OH can be generated, which is beneficial to the degradation of amide pollutants; while when the nickel-containing side faces the inlet water, the reaction sequence of dehalogenation followed by hydroxylation of halogenated pollutants has a thermodynamic advantage, resulting in faster degradation.

[0201] Using the Janus Fe-Ni SA@CF dual-film catalytic electrode from Example 3-1, a periodic degradation test of propranolol pollutants was conducted, with each period lasting 20 minutes. The test results can be found in [reference needed]. Figure 19 In 10 cycles, the Janus Fe-Ni SA@CF membrane cathode achieved a degradation rate of over 90% for propranolol within 20 minutes, with both iron and nickel ion concentrations in the solution being less than 70 μg / L. -1 This demonstrates that the double-film catalytic electrode of the present invention has good stability and a low risk of secondary pollution from metal ion leakage.

[0202] The Janus Fe-Ni SA@CF double-film catalytic electrode from Example 3-1 was used to treat secondary effluent from pharmaceutical wastewater. The wastewater treatment volume was 50 mL. During the degradation process, the wastewater was circulated in and out. Under normal temperature and pressure, the voltage between the anode and cathode was 3 V, and the membrane flux was 680 L / m³. -2 h -1 The wastewater flows from the surface loaded with iron single atoms to the surface loaded with nickel single atoms, and the treatment effect is as follows: Figure 20As shown, the Janus Fe-Ni SA@CF membrane cathode can reduce the chemical oxygen demand (COD) from 120 mg / L in one hour. -1 Reduced to 50mg / L -1 The absorption values ​​of UV254 and UV280 decreased by more than 78%, which demonstrates that the dual-film catalytic electrode of the present invention can rapidly remove organic matter containing unsaturated bonds.

[0203] Furthermore, three-dimensional fluorescence spectroscopy analysis (which can be used to analyze dissolved organic matter in water) was performed on the above-mentioned degraded pharmaceutical wastewater. Figure 21 As shown in (a), the main fluorescence intensity distribution of the pharmaceutical wastewater before treatment was in region V, indicating a high content of humic organic matter with poor biodegradability. Additionally, small amounts of fulvic acid-like substances (region III) and soluble microbial products (region IV) were also present. After treatment with Janus Fe-Ni SA@CF for 30 and 60 minutes, the fluorescence intensity distribution was as follows: Figure 21 As shown in (b) and (c), the fluorescence intensity in each region decreased significantly, indicating the effective removal of a large amount of dissolved organic matter, including recalcitrant humic substances. This demonstrates that the Janus Fe-Ni SA@CF membrane cathode can rapidly degrade a large amount of dissolved organic matter, including recalcitrant humic substances. These results indicate that the Janus Fe-Ni SA@CF membrane cathode has a significant effect on removing recalcitrant organic matter from wastewater and has promising practical application prospects.

[0204] The terms "first" and "second" used in this document are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0205] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0206] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A double-film catalytic electrode, characterized in that, The invention includes carbon skeleton fibers having a first surface and a second surface disposed opposite to each other. The first surface is loaded with a first transition metal single atom, and the second surface is loaded with a second transition metal single atom. One of the first transition metal single atom and the second transition metal single atom is used to induce the generation of oxidizing active species, and the other is used to induce the generation of reducing active species. The transition metal single atom includes at least one of iron, nickel, copper, cobalt, zinc, and manganese. The coordinating atoms that coordinate with the transition metal include at least one of nitrogen, phosphorus, sulfur, and oxygen, and the number of coordinating atoms that coordinate with a single atom of the transition metal is 1 to 6. The oxidizing active species include one or more of hydroxyl radicals, sulfate radicals, or singlet oxygen, and the reducing active species include one or two of atomic hydrogen and hydrated electrons.

2. A method for preparing the double-film catalytic electrode of claim 1, characterized in that, include: The first polymer, the first transition metal single-atom precursor, and the first organic solvent are uniformly mixed to obtain the first spinning solution; The second polymer, the second transition metal single-atom precursor, and the second organic solvent are uniformly mixed to obtain the second spinning solution; First, electrospinning is performed using the first spinning solution for a period of time, and then the second spinning solution is replaced to continue the second electrospinning to obtain a double-film intermediate. The double-film intermediate is pre-oxidized to obtain a pre-oxidized double-film. The pre-oxidized double-sided film is carbonized to obtain a double-sided film catalytic electrode.

3. The method according to claim 2, characterized in that, The first transition metal single-atom precursor includes at least one of the following: a metal-organic framework compound containing the first transition metal, a phthalocyanine salt containing the first transition metal, a mixture of a transition metal salt containing the first transition metal and a first organic compound. The second transition metal single-atom precursor includes at least one of a metal-organic framework compound containing the second transition metal, a phthalocyanine salt containing the second transition metal, or a mixture of a transition metal salt containing the second transition metal and a second organic compound.

4. The method according to claim 3, characterized in that, The mass ratio of the first polymer to the first transition metal single-atom precursor is 1:0.01 to 1:3; the mass ratio of the second polymer to the second transition metal single-atom precursor is 1:0.01 to 1:

3.

5. The method according to claim 3 or 4, characterized in that, The first spinning solution is prepared by method A, method B, or method C: Method A: Dissolve zinc nitrate and the first transition metal salt in a solvent, then add 2-methylimidazole solution to the mixture to obtain a mixed solution. After stirring, separating, and drying the mixed solution, the metal-organic framework compound containing the first transition metal is obtained. The metal-organic framework compound containing the first transition metal, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution. Method B: The phthalocyanine salt containing the first transition metal, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution; Method C: The first transition metal salt, the first organic compound, the first polymer, and the first organic solvent are uniformly mixed to obtain the first spinning solution, wherein the first organic compound includes at least one of phenanthroline and dopamine. The second spinning solution is prepared by method D, method E or method F: Method D: Dissolve zinc nitrate and the second transition metal salt in the solvent, then add 2-methylimidazole solution to the mixture, and obtain the metal-organic framework compound containing the second transition metal by stirring, separation and drying; uniformly mix the metal-organic framework compound containing the second transition metal, the second polymer and the second organic solvent to obtain the second spinning solution; Method E: The phthalocyanine salt containing the second transition metal, the second polymer, and the second organic solvent are uniformly mixed to obtain the second spinning solution; Method F: The second transition metal salt, the second organic compound, the second polymer, and the second organic solvent are uniformly mixed to obtain the second spinning solution, wherein the second organic compound includes at least one of phenanthroline and dopamine.

6. The method according to claim 5, characterized in that, At least one of the following conditions must be met in method A: The first transition metal salt includes at least one of nitrate and acetylacetone salt; The ratio of the first transition metal salt to the solvent is (0.05~5) mmol: 100 mL; In the first spinning solution, the amount of the metal-organic framework compound added is 0.08~0.12 g / mL of the first organic solvent, and the amount of the first polymer added is 0.08~0.12 g / mL of the first organic solvent; At least one of the following conditions must be met in method B: In the first spinning solution, the amount of phthalocyanine salt added is 0.01~0.2 mmol / mL of the first organic solvent, and the amount of the first polymer added is 0.08~0.12 g / mL of the first organic solvent; At least one of the following conditions must be met in method C: The first transition metal salt includes at least one of nitrate and acetylacetone salt; In the first spinning solution, the amount of the first transition metal salt added is 0.01~0.1 mmol / mL of the first organic solvent, the molar ratio of the first organic compound to the first transition metal salt is 4:1~8:1, and the amount of the first polymer added is 0.08~0.12 g / mL of the first organic solvent. At least one of the following conditions must be satisfied in method D: The second transition metal salt includes at least one of nitrates and acetylacetone salts; The ratio of the second transition metal salt to the solvent is (0.05~5) mmol: 100 mL; In the second spinning solution, the amount of the metal-organic framework compound added is 0.08~0.12 g / mL of the second organic solvent, and the amount of the second polymer added is 0.08~0.12 g / mL of the second organic solvent; At least one of the following conditions must be satisfied in method E: In the second spinning solution, the amount of phthalocyanine salt added is 0.01~0.2 mmol / mL of the second organic solvent, and the amount of the second polymer added is 0.08~0.12 g / mL of the second organic solvent; At least one of the following conditions must be satisfied in method F: The second transition metal salt includes at least one of nitrates and acetylacetone salts; In the second spinning solution, the amount of the second transition metal salt added is 0.01~0.1 mmol / mL of the second organic solvent, the molar ratio of the second organic compound to the second transition metal salt is 4:1~8:1, and the amount of the second polymer added is 0.08~0.12 g / mL of the second organic solvent.

7. The method according to claim 2, characterized in that, The pre-oxidation treatment conditions include: a temperature of 240~300℃ and a time of 0.5~3 h; The carbonization treatment conditions include: a temperature of 600~1400℃ and a time of 0.5~3 h.

8. The application of the double-film catalytic electrode according to claim 1 in the degradation of pollutants.

9. A system for catalytically degrading pollutants in water, characterized in that, include: anode; The cathode is the double-film catalytic electrode according to claim 1, or the double-film catalytic electrode prepared by any one of claims 2 to 7.

10. The catalytic degradation system for pollutants in water according to claim 9, characterized in that, During the degradation of the pollutants, at normal temperature and pressure, the voltage between the anode and the cathode is 0.5~5V, and the membrane flux of the wastewater is 50~2000 L / m³. -2 h -1 .

Images