Nitrogen-doped hollow carbon-supported iron-indium bimetal oxygen reduction catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oxygen reduction reaction catalysts, and provides a nitrogen-doped hollow carbon supported iron-indium bimetal oxygen reduction catalyst as well as a preparation method and application thereof. The invention reports that a novel nitrogen-doped hollow carbon supported bimetallic catalyst FeIn-NC is synthesized by pyrolyzing a metal-organic framework coated with PDA (polydopamine). The FeIn-NC catalyst prepared by the invention shows excellent electro-catalytic oxygen reduction activity in an alkaline medium, and meanwhile, the novel bimetallic iron indium catalyst with the hollow carbon support opens up a new breakthrough point for assembling a zinc air battery, and shows a huge application prospect in the fields of energy storage and conversion.

Description

Technical Field

[0001] This invention relates to the field of oxygen reduction reaction catalyst technology, specifically to a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst, its preparation method, and its application. Background Technology

[0002] Rechargeable metal-air batteries are considered promising next-generation energy conversion devices; however, the slow kinetics of the oxygen reduction reaction (ORR) at the cathode severely hinder their development. While Pt-based materials have become the benchmark electrocatalysts for improving ORR kinetics, their high cost, natural scarcity, and the clear correlation between methanol and Pt poisoning limit their large-scale application. Therefore, the search for efficient, low-cost Pt-free electrocatalysts has become a research hotspot in the field of metal-air batteries in recent years.

[0003] In recent years, metal-nitrogen-carbon (MNC) complexes have attracted much attention due to their high material utilization and remarkable catalytic activity. Among numerous MNC materials, Fe-NC catalysts exhibit excellent ORR activity and are expected to replace commercial Pt / C. However, the strong adsorption of the oxygen reduction intermediate *OH by the Fe-N4 site inhibits the desorption of *OH, thus limiting the ORR activity of Fe-NC. Therefore, it is necessary to further improve the oxygen reduction performance of Fe-NC. It has been reported that the strong orbital synergy between adjacent bimetallic centers in bimetallic catalysts can lower the reaction barrier and accelerate ORR kinetics, thus exhibiting good catalytic activity in ORR reactions. Currently, the design of bimetallic catalysts mainly focuses on the synergistic effect between dd orbitals. However, the large difference in reduction potential between d-block transition metals makes it difficult to precisely control the adsorption strength of *OH at active sites, thus affecting ORR catalytic activity and limiting its application potential. Recent studies have shown that p-block metal-controlled MNC materials exhibit satisfactory electrocatalytic activity. This is because the spherical symmetry of the p orbitals and the complexity of the d orbital shape make it easier for p-block metal atoms to hybridize with the d orbitals of transition metals. Furthermore, the energy of the p orbitals is higher than that of the d orbitals, and pd hybridization allows for more efficient orbital energy modulation compared to dd-orbital hybridization. Therefore, introducing p-block elements to modulate the Fe-N4 sites can further improve the oxygen reduction performance of Fe-NC materials. Summary of the Invention

[0004] This invention primarily aims to further improve the oxygen reduction performance of Fe-NC catalysts by developing and designing a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst (FeIn-NC). The synthesized FeIn-NC catalyst exhibits superior ORR activity compared to commercial Pt / C catalysts in alkaline electrolytes. Furthermore, FeIn-NC-based zinc-air batteries demonstrate stable open-circuit voltage and good charge-discharge durability.

[0005] The present invention is achieved through the following technical solution: adopting an outer layer protection strategy, coating a layer of polydopamine on the surface of FeIn-ZIF-8, and then carbonizing PDA@FeIn-ZIF-8 through high-temperature pyrolysis to form a FeIn-NC catalyst with nitrogen-doped hollow carbon support.

[0006] The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst described above includes the following steps:

[0007] Step 1: First, dissolve Zn(NO3)2·6H2O in methanol, dissolve 2-methylimidazole in an equal volume of methanol, mix the two solutions with stirring, react at room temperature for a certain time, centrifuge, wash with methanol, and dry to obtain ZIF-8 precursor;

[0008] Step 2: Dissolve the ZIF-8 precursor and tris(hydroxymethyl)aminomethane in a mixed solution of deionized water and ethanol to form solution A. Dissolve dopamine hydrochloride, Fe(NO3)3·9H2O and In(NO3)3·4.5H2O in deionized water to form solution B. Mix solution A and solution B with stirring, and continue stirring at room temperature for a certain period of time. Centrifuge, wash with ethanol, and dry to obtain PDA@FeIn-ZIF-8 powder.

[0009] Step 3: Pyrolyze the prepared PDA@FeIn-ZIF-8 under a protective gas and allow it to cool naturally to room temperature to obtain the prepared sample FeIn-NC.

[0010] In the preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst described above, in step one, the mass ratio of Zn(NO3)2·6H2O:2-methylimidazole is 4.78:10.52.

[0011] In the preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst described above, the reaction time in step one is 15-30 h with magnetic stirring at room temperature.

[0012] The above-mentioned method for preparing a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst includes a drying temperature of 70°C and a drying time of 12 h in step one, and a drying temperature of 70°C and a drying time of 12 h in step two.

[0013] In the preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst described above, in step two, the mass ratio of ZIF-8 precursor: tris(hydroxymethyl)aminomethane: dopamine hydrochloride: Fe(NO3)3·9H2O: In(NO3)3·4.5H2O is 200:120:28.4:30.3-68.2:16.9-45.1.

[0014] In the above-mentioned method for preparing a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst, the reaction time in step two should be 2-6 h with magnetic stirring at room temperature.

[0015] In the preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst described above, the pyrolysis in step three is carried out in a protective gas atmosphere at a pyrolysis temperature of 850-950℃ for a pyrolysis time of 1-3 h.

[0016] In the above-mentioned method for preparing a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst, the protective gas in step three should be argon or nitrogen.

[0017] The above-mentioned nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst is used in zinc-air batteries.

[0018] The above-mentioned application of a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst in a zinc-air battery is described. The zinc-air battery is constructed by using composite carbon paper supported by the above-mentioned nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst as an air cathode and zinc foil as an anode to construct an alkaline zinc-air battery.

[0019] The beneficial effects of this invention are:

[0020] This invention employs an outer-layer protection strategy to prepare a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst, FeIn-NC. The FeIn-NC catalyst exhibits excellent ORR performance in alkaline electrolytes, which stems from the strong pd orbital hybridization between the Fe and In atoms in the bimetallic reaction. Simultaneously, the hollow structure facilitates mass transport during the oxygen reduction reaction and maximizes the exposure of catalytic active sites, resulting in the superior ORR performance of FeIn-NC. FeIn-NC achieves a half-wave potential of 0.90 V and a limiting current density of 6.75 mA cm⁻¹ in alkaline media. -2 Meanwhile, FeIn-NC exhibits a direct four-electron transfer pathway for oxygen reduction and possesses excellent stability and resistance to methanol interference. The alkaline zinc-air battery using FeIn-NC as the cathode demonstrates superior performance, achieving an open-circuit voltage of 1.43 V and a peak power density of 116.20 mW / cm². -2It is close to the Pt / C catalyst-based battery (1.46 V, 93.01 mW cm⁻¹). -2 The findings of this invention provide a new approach for preparing MNC materials for use in ORR metal-air batteries that can replace platinum-driven cathodes. Attached Figure Description

[0021] Figure 1 SEM (a) and TEM (b) images of the Fe2In1-NC catalyst prepared in Example 2.

[0022] Figure 2 The images show the XRD patterns (a) before pyrolysis and (b) after pyrolysis of the FeIn-NC, Fe-NC, In-NC and NC catalysts prepared in Examples 1-7.

[0023] Figure 3 The Raman spectra of the Fe2In1-NC, Fe-NC, and In-NC catalysts prepared in Examples 2, 5, and 6 are shown.

[0024] Figure 4 The LSV curves of the FeIn-NC catalysts prepared in Examples 1-4 under alkaline conditions are shown.

[0025] Figure 5 LSV curves of Fe2In1-NC, Fe-NC, and In-NC catalysts prepared in Examples 2, 5, and 6, and commercial Pt / C under alkaline conditions.

[0026] Figure 6 The graph shows the H2O2 yield and electron transfer number obtained by the FeIn-NC catalysts prepared in Examples 1-4 under alkaline conditions.

[0027] Figure 7 LSV curves of the Fe2In1-NC catalyst prepared for Example 2 and commercial Pt / C under neutral (a) and acidic (b) conditions.

[0028] Figure 8 Stability tests of the Fe2In1-NC catalyst prepared in Example 2 and commercial Pt / C under alkaline conditions.

[0029] Figure 9 The graph shows the open-circuit voltage (a), discharge power density (b), and cycle charge-discharge (c) of the alkaline zinc-air battery assembled with the Fe2In1-NC catalyst prepared in Example 2. Specific implementation methods

[0030] Example 1 Synthesis of Fe3In1-NC

[0031] 1. Synthesis of ZIF-8

[0032] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0033] 2. Synthesis of PDA@Fe3In1-ZIF-8

[0034] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride, 68.2 mg of Fe(NO3)3·9H2O, and 16.9 mg of In(NO3)3·4.5H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred for 4 h at room temperature. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@Fe3In1-ZIF-8 powder.

[0035] 3. Synthesis of Fe3In1-NC

[0036] The obtained PDA@Fe3In1-ZIF-8 powder was subjected to a flow of argon gas at 5 °C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample Fe3In1-NC was obtained.

[0037] Example 2 Synthesis of Fe2In1-NC

[0038] 1. Synthesis of ZIF-8

[0039] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0040] 2. Synthesis of PDA@Fe2In1-ZIF-8

[0041] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride, 60.6 mg of Fe(NO3)3·9H2O, and 22.6 mg of In(NO3)3·4.5H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and stirred magnetically at room temperature for 4 h. The precipitate obtained by centrifugation was dried under vacuum at 70°C for 12 h to obtain PDA@Fe2In1-ZIF-8 powder.

[0042] 3. Synthesis of Fe2In1-NC

[0043] The obtained PDA@Fe2In1-ZIF-8 powder was subjected to a flow of argon gas at 5 °C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample Fe2In1-NC was obtained.

[0044] Example 3 Synthesis of Fe1In1-NC

[0045] 1. Synthesis of ZIF-8

[0046] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0047] 2. Synthesis of PDA@Fe1In1-ZIF-8

[0048] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride, 45.5 mg of Fe(NO3)3·9H2O, and 33.8 mg of In(NO3)3·4.5H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred for 4 h at room temperature. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@Fe1In1-ZIF-8 powder.

[0049] 3. Synthesis of Fe1In1-NC

[0050] The obtained PDA@Fe1In1-ZIF-8 powder was subjected to a flow of argon gas at 5 °C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample Fe1In1-NC was obtained.

[0051] Example 4 Synthesis of Fe1In2-NC

[0052] 1. Synthesis of ZIF-8

[0053] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0054] 2. Synthesis of PDA@Fe1In2-ZIF-8

[0055] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride, 30.3 mg of Fe(NO3)3·9H2O, and 45.1 mg of In(NO3)3·4.5H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred for 4 h at room temperature. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@Fe1In2-ZIF-8 powder.

[0056] 3. Synthesis of Fe1In2-NC

[0057] The obtained PDA@Fe1In2-ZIF-8 powder was subjected to a flow of argon gas at 5 °C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample Fe1In2-NC was obtained.

[0058] Example 5 Synthesis of Fe-NC

[0059] 1. Synthesis of ZIF-8

[0060] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0061] 2. Synthesis of PDA@Fe-ZIF-8

[0062] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride and 90.9 mg of Fe(NO3)3·9H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred for 4 h at room temperature. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@Fe-ZIF-8 powder.

[0063] 3. Synthesis of Fe-NC

[0064] The obtained PDA@Fe-ZIF-8 powder was subjected to a flow of argon gas at 5 °C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample Fe-NC was obtained.

[0065] Example 6 Synthesis of In-NC

[0066] 1. Synthesis of ZIF-8

[0067] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0068] 2. Synthesis of PDA@In-ZIF-8

[0069] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride and 67.7 mg of In(NO3)3·4.5H2O in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred for 4 h at room temperature. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@In-ZIF-8 powder.

[0070] 3. Synthesis of In-NC

[0071] The obtained PDA@In-ZIF-8 powder was subjected to a flow of argon gas at 5°C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared In-NC sample was obtained.

[0072] Example 7 Synthesis of NC

[0073] 1. Synthesis of ZIF-8

[0074] 10.52 g of 2-methylimidazole was dissolved in 100 mL of methanol, denoted as solution A. 4.78 g of Zn(NO3)2·6H2O was dissolved in 100 mL of methanol, denoted as solution B. Solutions A and B were rapidly mixed and magnetically stirred at room temperature for 24 h. The mixture was washed three times by centrifugation with methanol, and the resulting white powder was vacuum dried at 70°C for 12 h. Finally, ZIF-8 white powder was obtained.

[0075] 2. Synthesis of PDA@ZIF-8

[0076] Solution A was prepared by dissolving 200 mg of ZIF-8 precursor and 120 mg of tris(hydroxymethyl)aminomethane in 50 mL of deionized water and 50 mL of ethanol. Solution B was prepared by dissolving 28.4 mg of dopamine hydrochloride in 100 mL of deionized water. Solution B was then rapidly poured into solution A and magnetically stirred at room temperature for 4 h. The precipitate obtained by centrifugation was vacuum dried at 70°C for 12 h to obtain PDA@ZIF-8 powder.

[0077] 3. Synthesis of NC

[0078] The obtained PDA@ZIF-8 powder was subjected to a flow of argon gas at 5°C for 5 min. -1 The heating rate was maintained at 920℃ for 2 h. After natural cooling to room temperature, the prepared sample NC was obtained.

[0079] Example 8 Characterization of the nitrogen-doped hollow carbon-supported iron-indium bimetallic catalyst FeIn-NC

[0080] The Fe2In1-NC catalyst prepared in Example 2 was characterized by SEM and TEM, as follows: Figure 1 As shown. From Figure 1 The SEM (a) and TEM (b) images show that the Fe2In1-NC catalyst maintains a rhombic dodecahedral structure, and the dodecahedral surface is uniformly coated with a layer of polydopamine, proving the successful coating of polydopamine. Simultaneously, the catalyst exhibits a hollow structure due to surface shrinkage. XRD characterization was performed on the FeIn-NC, Fe-NC, In-NC, and NC catalysts prepared in Examples 1-7, as shown... Figure 2 As shown. From Figure 2 (a) It can be seen that the XRD pattern of the catalyst before pyrolysis is in excellent agreement with that of ZIF-8, showing the same crystal characteristics as ZIF-8, indicating that the addition of Fe, In and polydopamine did not change the structure of the precursor ZIF-8. The calcined catalysts, however, only showed graphitic carbon peaks, and no metallic crystalline phase was detected. Raman spectroscopy was performed on the Fe2In1-NC, Fe-NC, and In-NC catalysts prepared in Examples 2, 5, and 6. Figure 3 The image shows a Raman spectrum, indicating that the Fe2In1-NC catalyst exhibits an increased degree of defect, which is beneficial for improving the oxygen diffusion rate and thus enhancing catalytic activity.

[0081] Example 9: Oxygen Reduction Catalytic Activity Test of FeIn-NC Catalyst under Alkaline Conditions

[0082] Methods: The ORR performance of the FeIn-NC catalysts prepared in Examples 1-4 and the Fe-NC and In-NC control catalysts prepared in Examples 5 and 6 in oxygen-saturated 0.1 mol / L KOH solution was evaluated using a rotating disk electrode apparatus.

[0083] Linear sweep voltammetry (LSV) tests were performed on the FeIn-NC catalyst, such as... Figure 4 As shown. From Figure 4 It can be seen that the half-wave potential of the Fe2In1-NC catalyst in 0.1 mol / L KOH solution is 0.90 V, and the limiting current density is 6.75 mAcm⁻¹. -2 This is significantly superior to the Fe3In1-NC, Fe1In1-NC, and Fe1In2-NC catalysts prepared in Examples 1, 3, and 4, indicating that it has better ORR activity. Figure 5LSV testing showed that the Fe2In1-NC catalyst exhibited a higher onset potential and a larger limiting current density, significantly superior to the Fe-NC and In-NC catalysts prepared in Examples 5 and 6, and the commercial Pt / C catalyst. This is attributed to the introduction of In modulating the electronic structure of the Fe center. The oxygen reduction activity of the FeIn-NC catalyst in 0.1 mol / L KOH solution was further tested using a rotating ring-disk electrode apparatus. Figure 6 As shown. From Figure 6 It can be seen that the electron transfer number in the Fe2In1-NC-catalyzed ORR reaction is close to 4, and the hydrogen peroxide yield is 1.7%. The results indicate that the Fe2In1-NC-catalyzed ORR process is more inclined to a four-electron transfer pathway.

[0084] Example 10: Oxygen Reduction Catalytic Activity Test of FeIn-NC Catalyst under Neutral and Acidic Conditions

[0085] Methods: Referring to Example 9, the LSV of the Fe2In1-NC catalyst prepared in Example 2 and the commercial Pt / C catalyst were tested in oxygen-saturated 0.1 mol / L PBS and 0.5 mol / L H2SO4 solutions.

[0086] from Figure 7 As can be seen in (a), the E of the Fe2In1-NC catalyst in 0.1 mol / L PBS solution... 1 / 2 The value is 0.75V. Figure 7 In (b), E in a 0.5 mol / L H2SO4 solution 1 / 2 With a value of 0.74 V, its ORR activity is comparable to that of commercial Pt / C catalysts.

[0087] Example 11 Stability test of FeIn-NC catalyst under alkaline conditions

[0088] from Figure 8 As can be seen, after 10k CV cycles, the half-wave potential of the Fe2In1-NC catalyst decreased by only 5 mV, while the half-wave potential of commercial Pt / C decreased by 14 mV, indicating that the Fe2In1-NC catalyst has higher electrochemical stability.

[0089] Example 12 Performance Testing of an Alkaline Zinc-Air Battery Assembled with FeIn-NC Catalyst

[0090] Methods: The Fe2In1-NC catalyst ink prepared in Example 2 was uniformly drop-coated onto carbon paper to obtain carbon paper loaded with the Fe2In1-NC catalyst. An alkaline zinc-air battery was constructed using this carbon paper as the air cathode and zinc foil as the anode. The open-circuit voltage of the zinc-air battery was measured using OCPT technology on an electrochemical workstation, and the discharge curve of the zinc-air battery was measured using LSV technology.

[0091] exist Figure 9 As can be seen, the Fe2In1-NC-based alkaline zinc-air battery exhibits excellent performance, such as an open-circuit voltage as high as 1.43 V and a peak power density of 116.20 mW / cm². -2 It also exhibits good charge-discharge stability. These results fully demonstrate the potential of this catalyst in practical applications.

Claims

1. A nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst, characterized in that, FeIn-NC is obtained by pyrolyzing FeIn-ZIF-8 coated with polydopamine.

2. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 1, characterized in that, The method comprises the following steps: Step one: firstly, Zn(NO3)2·6H2O is dissolved in methanol, 2-methylimidazole is dissolved in an equal volume of methanol, and the two solutions are mixed under stirring, reacted at room temperature for a certain period of time, centrifuged and washed with methanol, and dried to obtain a ZIF-8 precursor; Step two: the ZIF-8 precursor and tris(hydroxymethyl) aminomethane are dissolved in a mixed solution of deionized water and ethanol to form solution A, dopamine hydrochloride, Fe(NO3)3·9H2O and In(NO3)3·4.5H2O are dissolved in deionized water to form solution B, and solution A and solution B are mixed under stirring, continuously stirred at room temperature for a certain period of time, centrifuged and washed with ethanol, and dried to obtain PDA@FeIn-ZIF-8 powder; Step three: the prepared PDA@FeIn-ZIF-8 is pyrolyzed under a protective gas, and after natural cooling to room temperature, the prepared sample FeIn-NC is obtained.

3. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: The certain period of time in step one is 15-30 h of magnetic stirring at room temperature.

4. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: The drying temperature in step one is 70℃, and the drying time is 12 h; the drying temperature in step two is 70℃, and the drying time is 12 h.

5. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: In step two, the mass ratio of ZIF-8 precursor: tris(hydroxymethyl) aminomethane: dopamine hydrochloride: Fe(NO3)3·9H2O: In(NO3)3·4.5H2O is 200:120:28.4:30.3-68.2:16.9-45.

1.

6. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: The certain period of time in step two should be 2-6 h of magnetic stirring at room temperature.

7. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: The pyrolysis in step three is pyrolysis at a temperature of 850-950℃ for 1-3 h in a protective gas atmosphere.

8. The preparation method of the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 2, characterized in that: The protective gas in step three should be argon or nitrogen.

9. The nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst of claim 1 in a zinc-air battery.

10. The use of a nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst according to claim 9 in a zinc-air battery, characterized in that, The zinc-air battery is constructed by using the nitrogen-doped hollow carbon-supported iron-indium bimetallic oxygen reduction catalyst of claim 1 as the air cathode and zinc foil as the anode.

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