Iron-iron-phosphorus 3-point electrocatalysts with asymmetric electronic structure and their applications
By constructing an iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure, the problems of slow ORR kinetics and high catalyst cost in zinc-air batteries were solved, achieving high catalytic activity and stability and improving battery energy density.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEAST GASOLINEEUM UNIV
- Filing Date
- 2026-03-15
- Publication Date
- 2026-06-02
AI Technical Summary
The four-electron oxygen reduction reaction (ORR) kinetics on the cathode of existing zinc-air batteries are slow, commercial platinum-carbon catalysts are expensive and prone to poisoning, and single-atom catalysts have low active site density, making it difficult to meet the requirements of high energy density.
By constructing an iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure, utilizing phosphorus atoms to regulate the electronic structure of iron sites, and combining it with a zeolite imidazole framework (ZIF-8) support and polymer coating, an iron-iron-phosphorus 3-point catalyst with an asymmetric electronic structure is formed through multi-step calcination treatment.
It improves catalytic activity and stability, optimizes the O–O bond breaking pathway, enhances the multi-site synergistic effect of the catalyst, and improves the energy density and catalytic activity of zinc-air batteries.
Smart Images
Figure CN122136376A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, specifically to an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure and its application. Background Technology
[0002] Zinc-air batteries, with their high theoretical energy density and zero carbon emissions, have become a promising sustainable energy conversion device, exhibiting higher energy conversion efficiency than traditional energy systems. However, the slow four-electron oxygen reduction reaction (ORR) kinetics at the zinc-air battery cathode limits their widespread application. Although commercial platinum-carbon has gained attention as an ORR electrocatalyst, it suffers from drawbacks such as high cost, insufficient durability, and susceptibility to poisoning. Iron-based catalysts, due to their partially occupied d-orbital structure, can effectively accept electrons from various oxygen-containing intermediates in the oxygen reduction reaction, making them a highly efficient and promising active metal for ORR. Therefore, constructing advanced iron-based electrocatalysts to enhance ORR catalytic activity and stability will contribute to improving the overall efficiency of zinc-air batteries.
[0003] Despite the significant advantages of single-atom catalysts (SACs) in terms of atom utilization and structural designability, their singular atomic coordination structure limits the diversity of their catalytic performance and the regulation of reaction pathways. Studies have shown that the highly symmetrical localized electron distribution in single-atom catalysts often restricts charge transfer between active sites and reactants, making it difficult to effectively activate certain inert chemical bonds. Furthermore, the lack of orbital overlap and electronic interactions between adjacent atoms at isolated active sites limits multi-site synergistic effects in the catalytic process, and the relatively low site density makes it difficult to meet the high energy density requirements of zinc-air batteries.
[0004] By precisely and directionally introducing binuclear, trinuclear, or multinuclear sites, constructing asymmetric active site electronic structures and endowing them with strong electronic coupling, the ability to regulate complex reaction pathways can be enhanced, promoting the breaking of O-O bonds and generating H₂O with high selectivity via a four-electron pathway. Furthermore, the directional introduction of heteroatoms such as nitrogen, sulfur, boron, and phosphorus can further break the symmetry of active sites, forcing a redistribution of local charges within the active sites. By modulating the electronic structure of metal sites, the adsorption strength of oxygen-containing intermediates can be effectively optimized, the reaction energy barrier lowered, and catalytic activity enhanced. Summary of the Invention
[0005] One object of the present invention is to provide an iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure, which is used to solve the problem that the low site density of existing catalysts makes it difficult to meet the high energy density requirements of zinc-air batteries; another object of the present invention is to provide the application of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure.
[0006] The technical solution adopted by this invention to solve its technical problem is as follows: This iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure is prepared by the following method: Step 1: Disperse zinc and iron salts uniformly in a mixed solution of N,N-dimethylformamide and methanol, denoted as solution A; disperse 2-methylimidazole uniformly in the mixed solution of N,N-dimethylformamide and methanol, denoted as solution B; quickly pour solution B into solution A, stir at room temperature, centrifuge, and dry to obtain a pale yellow powder; the molar ratio of 2-methylimidazole to the metal salt is 4:1-40:1, the number of moles of the metal salt is the sum of the number of moles of zinc and iron salts, and the molar ratio of zinc to iron salt is 8:1-100:1; Step 2: Disperse the pale yellow powder evenly in a methanol solution, add tannic acid solution and stir at room temperature, centrifuge, and vacuum dry to obtain a gray-green powder, denoted as Fe@ZIF-8; the volume ratio of tannic acid solution to methanol is 2:1-30:1. Step 3: Disperse Fe@ZIF-8 and p-phenylenediamine in a tetrahydrofuran solution, add a phosphorus source and triethylamine, stir at a certain temperature, centrifuge, and vacuum dry to obtain polymer-coated Fe@ZIF-8; Step 4: The Fe@ZIF-8 is first calcined in an argon atmosphere, and then calcined in a carbon dioxide atmosphere to obtain a phosphorus-doped iron single-atom catalyst. Step 5: The phosphorus-doped iron single-atom catalyst is ball-milled with iron salt and phthalocyanine, and then subjected to high-temperature treatment by Joule heating under argon protection to obtain an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure.
[0007] In step one of the above scheme, the zinc salt is one of zinc stearate, zinc glycinate, basic zinc carbonate, polypyrrolidone zinc, zinc lactate, zinc methoxide, zinc oxalate, zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, zinc gluconate, and zinc dihydrogen phosphate; the iron salt is one of ferric carbonate, ferric ethoxide, porphyrin iron, ferrous sulfate, ferrous chloride, ferric pyrophosphate, ferric sulfate, ferric nitrate, ferric acetate, ferric chloride, ferric acetylacetone, ferrocene, and iron(III) phthalocyanine chloride.
[0008] In step one of the above scheme, the volume ratio of N,N-dimethylformamide to methanol in the mixed solution is 1:1-80:1, the stirring time is 0.5-48 h, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48 h.
[0009] In step two of the above scheme, the concentration of the tannic acid solution is 0.5 g / L. -1 -160 g L -1The stirring time is 0.5-48h, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48h.
[0010] In step three of the above scheme, the phosphorus source is one of the following: isofenphos, fumonisin-oxygen, sodium phosphenytoin, heptenphos, metaphosphate, polyphosphate, isofenphos oxyphosphate, naphthylphosphide, disodium hydrogen phosphate, melamine phosphate, phytic acid, hexachlorotriphosphazene, sodium hypophosphite, and sodium dihydrogen phosphate.
[0011] In step three of the above scheme, the molar ratio of phosphorus source to iron salt mentioned in step one is 1:0.2-1:100, the molar ratio of p-phenylenediamine to phosphorus source is 1:1-20:1, the molar ratio of triethylamine to phosphorus source is 10:1-220:1, the stirring temperature is 40-160ºC, the stirring time is 0.5-48 h, the stirring temperature is 40-160 ºC, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48 h.
[0012] In step four of the above scheme, the calcination temperature in an argon atmosphere is 300-1500 ºC, the heating rate is 0.5-30ºC / min, and the calcination time is 0.5-20 h; the calcination temperature in a carbon dioxide atmosphere is 300-1500 ºC, the heating rate is 0.5-30 ºC / min, and the calcination time is 0.5-20 h.
[0013] In step five of the above scheme, the iron salt is one of the following: iron citrate, iron sucrose, iron oxalate, iron oleate, ferrous carbonate, iron ethoxide, iron porphyrin, ferric iron, sodium chlorophyll iron, bis(pentamethylcyclopentadiene) iron, iron nitrate, iron acetate, ferric chloride, iron acetylacetone, ferrous sulfate, ferrocene, and iron(III) phthalocyanine chloride.
[0014] In step five of the above scheme, the molar ratio of phthalocyanine to iron salt is 0.2:1-200:1, the ball milling speed is 100-600 rpm, the ball milling time is 0.5-10 h, the Joule heating temperature is 800-3000 ºC, and the isothermal time is 1-300 s.
[0015] The aforementioned iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure is applied to the air cathode reaction in a zinc-air battery.
[0016] Beneficial effects: 1. This invention constructs an asymmetric local coordination environment by directionally introducing phosphorus atoms and precisely controlling the electronic structure of diatomic iron sites. Due to phosphorus's low electronegativity and large atomic radius, local strain and asymmetric charge distribution can be introduced, optimizing the O–O bond breaking pathway and enhancing catalytic activity.
[0017] 2. This invention prepares hollow Fe@ZIF-8 by etching with tannic acid, then coats it with polymer and pyrolyzes it to obtain a highly exposed Fe single-atom catalyst.
[0018] 3. This invention utilizes a defect engineering strategy to perform secondary pyrolysis in a CO2 atmosphere to increase the porosity of the material (mainly due to defect formation caused by atomic absence), thereby obtaining a catalyst with a hierarchical porous structure. This enhances the metal adsorption capacity and facilitates subsequent regulation of bimetallic sites.
[0019] 4. This invention encapsulates an iron salt precursor using a zeolite imidazole framework (ZIF-8) as a confined support. After polymer coating, a two-step calcination process achieves structural transformation: first, carbonization / graphitization in argon enhances the conductivity of the carbon support and reduces metal species; then, etching with carbon dioxide (CO2) yields an iron single-atom catalyst rich in defect sites. Based on this, an iron source is reintroduced and treated using Joule heating to construct an iron-iron-phosphorus three-atom site electrocatalyst with an asymmetric electronic structure, applicable to the air cathode reaction in a zinc-air battery. This invention's method for preparing three-site catalysts provides a novel approach to the synthesis of three-site catalysts. Attached image description: Figure 1 This is the XRD pattern of the iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure in Example 1.
[0020] Figure 2 This is a TEM image of the iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure in Example 1.
[0021] Figure 3 The linear sweep voltammetry curves of the iron-iron-phosphorus three-point electrocatalyst with asymmetric electronic structure in Example 1 and the control sample in 0.1 MKOH are shown.
[0022] Figure 4 The linear sweep voltammetry curves of the iron-iron-phosphorus three-point electrocatalyst with asymmetric electronic structure in Example 1 and the control sample in 0.5 MH2SO4 are shown.
[0023] Figure 5 The polarization curves and power density diagrams of the zinc-air battery assembled with the iron-iron-phosphorus three-point electrocatalyst with the asymmetric electronic structure in Example 1 and the control sample Pt / C+RuO2 as the air cathode are shown. Detailed Implementation
[0024] The present invention will be further described below with reference to the accompanying drawings: Example 1
[0025] This iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure was prepared by the following method: Step 1: Disperse 1.4 g of zinc nitrate hexahydrate and 119 mg of ferric nitrate in a 30 mL mixture of N,N-dimethylformamide and methanol (N,N-dimethylformamide and methanol volume ratio 4:1), denoted as solution A; disperse 1.62 g of 2-methylimidazole in a 30 mL mixture of N,N-dimethylformamide and methanol, denoted as solution B; quickly pour solution B into solution A, stir at room temperature for 24 h, centrifuge, and vacuum dry at 80 ºC to obtain a pale yellow powder; Step 2: Take 300 mg of the solid powder obtained in Step 1 and disperse it in 10 mL of methanol solution, then add 50 mL of tannic acid solution (2 g / L). -1 Stir for 0.5 h, centrifuge, and vacuum dry to obtain a gray-green powder, denoted as Fe@ZIF-8; Step 3: Disperse 200 mg Fe@ZIF-8 and 75 mg p-phenylenediamine in 50 mL of tetrahydrofuran solution. First, add 80 mg of hexachlorotriphosphazene to the above solution, and then slowly add 4 mL of triethylamine to the above solution. Stir at 40 ºC for 6 h, centrifuge, and vacuum dry to obtain polymer-coated Fe@ZIF-8. Step 4: The Fe@ZIF-8 polymer-coated catalyst obtained in Step 3 is first calcined in an argon atmosphere at a temperature of 950 ºC for 2 h at a heating rate of 5 ºC / min; then calcined in a CO2 atmosphere at a heating rate of 5 ºC / min at a temperature of 800 ºC for 0.5 h to obtain a phosphorus-doped iron single-atom catalyst. Step 5: The 100 mg phosphorus-doped iron single-atom catalyst, 8.1 mg iron(III) phthalocyanine chloride, and 24.27 mg phthalocyanine obtained in Step 4 were ball-milled and then subjected to Joule heat treatment under an argon atmosphere at a heating temperature of 1200 ºC for 10 s to obtain an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure, denoted as Fe2 / NCP.
[0026] The iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure obtained in Example 1 above was characterized.
[0027] like Figure 1 The image shows the XRD pattern of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure in Example 1. The diffraction peaks at 24º and 44º are characteristic peaks of graphite carbon, and there are no diffraction peaks of nanoparticles.
[0028] like Figure 2The image shown is a TEM image of the iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure in Example 1. The catalyst obtained in Example 1 has a polyhedral morphology and a hollow structure with an average diameter of about 320 nm. Example 2
[0029] This iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure was prepared by the following method: Step 1: Disperse 1.4 g of zinc nitrate hexahydrate and 56 mg of ferric acetate in a 30 mL mixture of N,N-dimethylformamide and methanol (N,N-dimethylformamide and methanol volume ratio 4:1), denoted as solution A; disperse 1.62 g of 2-methylimidazole in a 30 mL mixture of N,N-dimethylformamide and methanol, denoted as solution B; quickly pour solution B into solution A, stir at room temperature for 24 h, centrifuge, and then vacuum dry at 80 ºC to obtain a solid powder; Step 2: Take 300 mg of the solid powder obtained in Step 1 and disperse it in 10 mL of methanol solution, then add 50 mL of tannic acid solution (2 g / L). -1 Stir for 0.5 h, centrifuge, and vacuum dry to obtain a gray-green powder, denoted as Fe@ZIF-8; Step 3: Disperse 200 mg Fe@ZIF-8 and 75 mg p-phenylenediamine in 50 mL of tetrahydrofuran solution. First, add 80 mg of hexachlorotriphosphazene to the above solution, and then slowly add 4 mL of triethylamine to the above solution. Stir at 40 ºC for 6 h, centrifuge, and vacuum dry to obtain polymer-coated Fe@ZIF-8. Step 4: The Fe@ZIF-8 polymer-coated catalyst obtained in Step 3 is first calcined in an argon atmosphere at a temperature of 950 ºC for 2 h at a heating rate of 5 ºC / min; then calcined in a CO2 atmosphere at a heating rate of 5 ºC / min at a temperature of 800 ºC for 0.5 h to obtain a phosphorus-doped iron single-atom catalyst. Step 5: The 100 mg phosphorus-doped iron single-atom catalyst, 5.6 mg ferrome, and 24.27 mg phthalocyanine obtained in Step 4 were ball-milled and then subjected to Joule heat treatment under an argon atmosphere at a heating temperature of 1200 ºC for 10 s to obtain an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure. Example 3
[0030] This iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure was prepared by the following method: Step 1: Disperse 1.4 g of zinc nitrate hexahydrate and 56 mg of ferric acetate in a 30 mL mixture of N,N-dimethylformamide and methanol (N,N-dimethylformamide and methanol volume ratio 4:1), denoted as solution A; disperse 1.62 g of 2-methylimidazole in a 30 mL mixture of N,N-dimethylformamide and methanol, denoted as solution B; quickly pour solution B into solution A, stir at room temperature for 24 h, centrifuge, and then vacuum dry at 80 ºC to obtain a solid powder; Step 2: Take 300 mg of the solid powder obtained in Step 1 and disperse it in 10 mL of methanol solution, then add 50 mL of tannic acid solution (2 g / L). -1 Stir for 0.5 h, centrifuge, and vacuum dry to obtain a gray-green powder, denoted as Fe@ZIF-8; Step 3: Disperse 200 mg Fe@ZIF-8 and 75 mg p-phenylenediamine in 50 mL of tetrahydrofuran solution. First, add 80 mg of hexachlorotriphosphazene to the above solution, and then slowly add 4 mL of triethylamine to the above solution. Stir at 40 ºC for 8 h. After centrifugation and vacuum drying, polymer-coated Fe@ZIF-8 is obtained. Step 4: The Fe@ZIF-8 polymer-coated catalyst obtained in Step 3 is first calcined in an argon atmosphere at a temperature of 950 ºC for 2 h at a heating rate of 5 ºC / min; then calcined in a CO2 atmosphere at a heating rate of 5 ºC / min at a temperature of 800 ºC for 0.5 h to obtain a phosphorus-doped iron single-atom catalyst. Step 5: The 100 mg phosphorus-doped iron single-atom catalyst, 4.7 mg iron acetylacetone, and 24.27 mg phthalocyanine obtained in Step 4 were ball-milled and then subjected to Joule heat treatment under an argon atmosphere at a heating temperature of 1200 ºC for 10 s to obtain an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure.
[0031] The application of the aforementioned iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure in catalyzing the oxygen reduction reaction is as follows: 5 mg of Examples 1-3 were dispersed in a mixed solution of 960 mL isopropanol and 40 mL Nafion (5 wt%), and sonicated for 2 h to obtain a uniformly dispersed slurry. Then, 11 μL of the slurry was transferred by pipette and uniformly coated on the surface of the glassy carbon electrode. After drying in air, the working electrode was prepared.
[0032] Comparative Example 1: The only difference between this comparative example and Example 1 is that p-phenylenediamine, hexachlorotriphosphazene, tetrahydrofuran, and triethylamine, denoted as Fe2 / NC, were not used in this comparative example.
[0033] Comparative Example 2: The only difference between this comparative example and Example 1 is that iron(III) phthalocyanine chloride, p-phenylenediamine, hexachlorotriphosphazene, tetrahydrofuran, and triethylamine, denoted as Fe1 / NC, were not used in this comparative example.
[0034] Comparative Example 3: The only difference between this comparative example and Example 1 is that ferric nitrate and iron(III) phthalocyanine chloride, denoted as NCP, were not used in this comparative example.
[0035] Comparative Example 4: The only difference between this comparative example and Example 1 is that ferric nitrate, iron(III) phthalocyanine chloride, p-phenylenediamine, hexachlorotriphosphazene, tetrahydrofuran, and triethylamine (denoted as NC) were not used in this comparative example.
[0036] Comparative Example 5: This comparative example is a commercial Pt / C (Pt mass fraction of 20 wt%).
[0037] The application of the aforementioned iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure in catalyzing the oxygen reduction reaction is as follows: 5 mg of Examples 1-3 and Comparative Examples 1-5 were dispersed in a mixed solution of 960 mL isopropanol and 40 mL Nafion (5 wt%), and sonicated for 2 h to obtain a uniformly dispersed slurry. Then, 11 μL of the slurry was transferred by pipette and uniformly coated on the surface of the glassy carbon electrode. After drying in air, the working electrode was prepared.
[0038] like Figure 3 The linear sweep voltammetry curves of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure from Example 1 and the control sample are shown in 0.1 M KOH. The onset potential and half-wave potential of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure obtained from Example 1 are 1.08 V and 0.94 V, respectively, which are superior to the commercial Pt / C of Comparative Example 5 (1.02 V and 0.86 V). The onset potential and half-wave potential of the catalyst obtained from Comparative Example 1 are 1.02 V and 0.90 V, respectively; those from Comparative Example 2 are 1.02 V and 0.87 V; those from Comparative Example 3 are 0.95 V and 0.81 V; and those from Comparative Example 4 are 0.94 V and 0.79 V.
[0039] like Figure 4The linear sweep voltammetry curves of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure from Example 1 and the control sample are shown in 0.5 M H₂SO₄. The onset potential and half-wave potential of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure obtained from Example 1 are 0.93 V and 0.82 V, respectively, which are close to those of the commercial Pt / C in Comparative Example 5 (0.97 V and 0.84 V). The onset potential and half-wave potential of the catalyst obtained from Comparative Example 1 are 0.85 V and 0.73 V, respectively; those from Comparative Example 2 are 0.86 V and 0.67 V; those from Comparative Example 3 are 0.83 V and 0.64 V; and those from Comparative Example 4 are 0.80 V and 0.51 V.
[0040] like Figure 5 The polarization curves and power density diagrams of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure, as shown in Example 1, and the comparative sample Pt / C+RuO2 as the air cathode in a zinc-air battery assembly are presented. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure obtained in Example 1 exhibits a significantly better peak power density than commercial Pt / C+RuO2.
Claims
1. A three-point electrocatalyst with an asymmetric electronic structure, characterized in that: This iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure was prepared by the following method: Step 1: Disperse zinc and iron salts uniformly in a mixed solution of N,N-dimethylformamide and methanol, denoted as solution A; disperse 2-methylimidazole uniformly in the mixed solution of N,N-dimethylformamide and methanol, denoted as solution B; quickly pour solution B into solution A, stir at room temperature, centrifuge, and dry to obtain a pale yellow powder; the molar ratio of 2-methylimidazole to the metal salt is 4:1-40:1, the number of moles of the metal salt is the sum of the number of moles of zinc and iron salts, and the molar ratio of zinc to iron salt is 8:1-100:1; Step 2: Disperse the pale yellow powder evenly in a methanol solution, add tannic acid solution and stir at room temperature, centrifuge, and vacuum dry to obtain a gray-green powder, denoted as Fe@ZIF-8; the volume ratio of tannic acid solution to methanol is 2:1-30:
1. Step 3: Disperse Fe@ZIF-8 and p-phenylenediamine in a tetrahydrofuran solution, add a phosphorus source and triethylamine, stir at a certain temperature, centrifuge, and vacuum dry to obtain polymer-coated Fe@ZIF-8; Step 4: The Fe@ZIF-8 is first calcined in an argon atmosphere, and then calcined in a carbon dioxide atmosphere to obtain a phosphorus-doped iron single-atom catalyst. Step 5: The phosphorus-doped iron single-atom catalyst is ball-milled with iron salt and phthalocyanine, and then subjected to high-temperature treatment by Joule heating under argon protection to obtain an iron-iron-phosphorus three-point electrocatalyst with an asymmetric electronic structure.
2. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 1, characterized in that: In step one, the zinc salt is one of zinc stearate, zinc glycinate, basic zinc carbonate, polypyrrolidone zinc, zinc lactate, zinc methoxide, zinc oxalate, zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, zinc gluconate, and zinc dihydrogen phosphate; the iron salt is one of ferric carbonate, ferric ethoxide, porphyrin iron, ferrous sulfate, ferrous chloride, ferric pyrophosphate, ferric sulfate, ferric nitrate, ferric acetate, ferric chloride, ferric acetylacetone, ferrocene, and iron(III) phthalocyanine chloride.
3. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 2, characterized in that: In step one, the volume ratio of N,N-dimethylformamide to methanol in the mixed solution is 1:1-80:1, the stirring time is 0.5-48 h, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48 h.
4. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 3, characterized in that: The concentration of the tannic acid solution in step two is 0.5 g / L. -1 -160 g L -1 The stirring time is 0.5-48 h, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48 h.
5. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 4, characterized in that: In step three, the phosphorus source is one of the following: isofenphos, fusoxonium-oxygen, sodium phenytoin, heptenphos, metaphosphate, polyphosphate, isofenphos oxyphosphate, naphthylphosphide, disodium hydrogen phosphate, melamine phosphate, phytic acid, hexachlorotriphosphazene, sodium hypophosphite, and sodium dihydrogen phosphate.
6. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 5, characterized in that: In step three, the molar ratio of phosphorus source to iron salt in step one is 1:0.2-1:100, the molar ratio of p-phenylenediamine to phosphorus source is 1:1-20:1, and the molar ratio of triethylamine to phosphorus source is 10:1-220:
1. The stirring temperature is 40-160 ºC, the stirring time is 0.5-48 h, the vacuum drying temperature is 80-120 ºC, and the drying time is 8-48 h.
7. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 6, characterized in that: In step four, the calcination temperature in an argon atmosphere is 300-1500 ºC, the heating rate is 0.5-30 ºC / min, and the calcination time is 0.5-20 h; the calcination temperature in a carbon dioxide atmosphere is 300-1500 ºC, the heating rate is 0.5-30 ºC / min, and the calcination time is 0.5-20 h.
8. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 7, characterized in that: The iron salt in step five is one of the following: iron citrate, iron sucrose, iron oxalate, iron oleate, ferrous carbonate, iron ethoxide, iron porphyrin, ferric iron, sodium chlorophyll iron, bis(pentamethylcyclopentadiene) iron, iron nitrate, iron acetate, ferric chloride, iron acetylacetone, ferrous sulfate, ferrocene, and iron(III) phthalocyanine chloride.
9. The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure according to claim 8, characterized in that: In step five, the molar ratio of phthalocyanine to iron salt is 0.2:1-200:1, the ball milling speed is 100-600 rpm, and the ball milling time is 0.5-10 h; the Joule heating temperature is 800-3000 ºC, and the isothermal time is 1-300 s.
10. The application of the iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure as described in claim 9, characterized in that: The iron-iron-phosphorus 3-point electrocatalyst with an asymmetric electronic structure is applied to the air cathode reaction in a zinc-air battery.