Eucalyptus-shaped Co-Fe2P nitrogen-doped carbon electrocatalyst as well as preparation method and application of eucalyptus-shaped Co-Fe2P nitrogen-doped carbon electrocatalyst
By preparing eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst, the problem of slow ORR kinetics in aluminum-air batteries was solved, the specific surface area and electrocatalytic performance of the catalyst were improved, and efficient and stable electrochemical reactions were achieved.
Patent Information
- Application Number
- CN202510719465.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-09-05
AI Technical Summary
The oxygen reduction reaction (ORR) kinetics of existing aluminum-air batteries are slow, making it difficult to break the strong O=O bond, resulting in limited power density. In addition, platinum-based materials are expensive and scarce, limiting their large-scale commercial application.
A eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst was synthesized using a one-step hydrothermal process. A catalyst with a eucalyptus structure was formed through a composite material of MoO3 nanorods, polyamic acid and ZIF-8, which increased the active sites and local electric field, optimized the Fe-N atomic bridge structure, and promoted the adsorption and desorption process of oxygen intermediates.
The specific surface area and electronic conductivity of the catalyst were significantly improved, the adsorption/desorption energy barrier of oxygen intermediates was reduced, the chemical stability and electrocatalytic performance of the catalyst were enhanced, and the long-term stability and high voltage performance matching those of commercial Pt/C catalysts were achieved.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalyst preparation, and more particularly to a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and a preparation method and application thereof. Background Art
[0002] With increasingly severe environmental challenges and rapidly growing global energy demand, the development of sustainable, green materials for metal-air batteries (such as aluminum-air batteries (AABs)) is imperative. AABs offer a high theoretical energy density of 8100 Wh / kg, along with high cost-effectiveness, environmental sustainability, and safety. They employ an aluminum anode / air cathode / electrolyte structure, following the typical primary battery design. Their innovation lies in achieving sustained discharge through mechanical anode replacement regeneration.
[0003] However, the power density of AABs is limited by the sluggish kinetics of the oxygen reduction reaction (ORR), primarily due to the difficulty in breaking the strong O=O bond (bond energy of 498 kJ / mol). Therefore, there is an urgent need to develop advanced catalysts to lower the energy barrier for ORR. Although platinum-based materials have shown efficient catalytic activity for ORR, their high cost and scarcity hinder large-scale commercial applications.
[0004] Therefore, designing highly active and cost-effective non-precious metal-based ORR catalysts for AABs has become a major challenge. Typically, the performance of single-component oxygen electrode materials in catalyzing the oxygen reduction reaction is unsatisfactory. This is largely due to the interaction dynamics between the active sites and specific oxygen-containing intermediates. The binding between the two is either too strong or too weak, thereby destroying the linear scaling relationship necessary to achieve equilibrium adsorption and desorption processes.
[0005] To overcome this problem, integrating ORR active sites at the interface is an effective strategy for constructing efficient oxygen reduction electrodes. In these multi-component catalyst systems, ORR activity usually originates from the joint action of multi-component sites, thereby alleviating the adsorption / desorption process of oxygen intermediates. Although breakthroughs have been made in the current field, the research focus is still on the analysis of the structure-activity relationship of active sites, and there is a lack of systematic research on the directional construction of interfacial electron transport channels. Conventional synthesis strategies are prone to cause disordered distribution or weak interaction assembly of catalytic sites, forming metastable interface structures, resulting in sluggish charge transfer kinetics. This phenomenon highlights the importance of constructing a cross-scale atomic-level interface bridging system. The core scientific issue is how to break through the electron transfer bottleneck through precise interface regulation and achieve a step-by-step improvement in electrocatalytic performance. Summary of the Invention
[0006] One of the purposes of the present invention is to provide a method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst. The catalyst prepared by this method has a special eucalyptus structure. This structure has a higher specific surface area, so it can accommodate more active sites, and there is a local strong electric field nearby, which can increase the OH - concentration, which helps the adsorption and desorption process of oxygen intermediates and improves the electrocatalytic performance.
[0007] To achieve the above object, the present invention adopts the following technical solutions:
[0008] A method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst utilizes a one-step hydrothermal process to synthesize MoO3 nanorods. Next, polyamic acid (PAA), a polyimide (PI) precursor, is synthesized by condensing pyromellitic dianhydride (PMDA) and ethylenediamine (EDA) in N,N-dimethylformamide. Under vigorous stirring, PAA undergoes an in-situ polycondensation reaction at 145-165°C in the presence of MoO3 nanorods, forming PI on the surface of the MoO3 nanorods. The PI nanosheets are periodically arranged along the longitudinal axis of the MoO3 nanorods in an edge-oriented manner, resulting in a composite material with a eucalyptus-like structure. ZIF-8 is then grown on the MoO3 / PI to form MoO3 / PI@ZIF-8. After etching away the MoO3 nanorods using a phytic acid solution, the MoO3 / PI@ZIF-8 transforms into a PI@ZIF-8 tube-sheet superstructure with a hollow interior. Subsequently, Fe and Co species were introduced and adsorbed on the PI@ZIF-8 tube-sheet superstructure substrate. Finally, after high-temperature calcination, the PI@ZIF-8 tube-sheet superstructure with adsorbed cobalt and iron ions was transformed into the target product, eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst.
[0009] The specific steps include:
[0010] Preparation of S1 and MoO3
[0011] Ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 4H2O) was dissolved in a mixture of concentrated nitric acid (68%) and deionized water to a concentration of 0.00348-0.0348 g / mL. The solution was magnetically stirred at room temperature for 20 minutes to form precursor solution A. The precursor suspension was injected into a 100 mL polytetrafluoroethylene-lined autoclave and hydrothermally treated at 160-200°C for 18-24 hours. After the system was naturally cooled to room temperature, the white product was collected by centrifugation, washed three times with alternating deionized water and ethanol, and then dried in a vacuum drying oven at 40-60°C for 12-18 hours to produce MoO3 nanorods. In solution A, the concentrated nitric acid and deionized water were mixed in a volume ratio of (0.1-0.3):1.
[0012] Preparation of S2, MoO3 / PI
[0013] Ethylenediamine (EDA) was dispersed in N,N-dimethylformamide (DMF) at a concentration of 0.002-0.02 g / mL to obtain solution B. Pyromellitic dianhydride (PMDA) was dissolved in DMF at a concentration of 0.006-0.06 g / mL to obtain solution C. Solutions B and C were thoroughly mixed in a 1:1 volume ratio and magnetically stirred at room temperature for 6 hours to form a transparent polyamic acid (PAA) prepolymer solution. After dilution with DMF, mechanical stirring was continued for 10 minutes to obtain a homogeneous system, obtaining solution D. Molybdenum trioxide nanorods were ultrasonically dispersed in DMF to prepare a stable suspension at a concentration of 0.001-0.01 g / mL, obtaining solution E. The two phases were thoroughly mixed in a 1:1.2 volume ratio and transferred to a 500 mL two-necked round-bottom flask equipped with a mechanical stirrer. Polymerization was carried out in an oil bath at 145-165°C with a gradient temperature increase, maintaining vigorous reflux and stirring for 1-2 hours to complete the polymerization process. After the reaction is terminated, the product is separated by high-speed centrifugation, washed three times with DMF-ethanol alternately, and then dried in a vacuum drying oven at 40-60° C. for 12-18 h to obtain a MoO 3 / polyimide (MoO 3 / PI) nanocomposite material;
[0014] Preparation of S3, MoO3 / PI@ZIF-8
[0015] MoO3 / PI and zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in methanol solution and stirred for 3-5 hours. Then, 2-methylimidazole was added to the solution. After stirring for 0.5-2 hours, the solution was allowed to stand for 18-24 hours to obtain solution F, in which the concentration of MoO3 / PI was 0.001-0.01 g / mL, the concentration of zinc nitrate hexahydrate was 0.002-0.02 g / mL, and the concentration of 2-methylimidazole was 0.002-0.02 g / mL. Subsequently, the final product was washed and dried at 40-60°C for 18-24 hours to obtain MoO3 / PI@ZIF-8;
[0016] S4. Preparation of PI@ZIF-8 tube-sheet superstructure
[0017] MoO3 / PI@ZIF-8 was dispersed in ultrapure water at a concentration of 0.01-0.1 g / mL to obtain Solution G. Subsequently, phytic acid was added at a concentration of 0.1-1.0 M, and the mixture was allowed to react at 80-100°C for 3-5 hours. After the reaction, the resulting product was washed and then dried at 40-60°C for 18-24 hours to obtain the PI@ZIF-8 tube-sheet superstructure.
[0018] S5. Preparation of PI@ZIF-8 tube-sheet superstructures with adsorption of cobalt and iron ions
[0019] The PI@ZIF-8 tube-sheet superstructure was weighed as a support matrix and co-dissolved with bimetallic precursors (ferric nitrate nonahydrate (Fe(NO3)3·9H2O) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O)) in a methanol solvent system to obtain solution H. The concentrations of the PI@ZIF-8 tube-sheet superstructure were 0.002-0.02 g / mL, the ferric nitrate nonahydrate (0.0005-0.005 g / mL), and the cobalt nitrate hexahydrate (0.0005-0.005 g / mL). After dispersion by magnetic stirring, the superstructure was aged at room temperature for 18-24 hours to complete self-assembly. The composite precipitate was obtained by centrifugation and washed with alternating methanol / deionized water to remove unreacted products. Finally, the composite catalytic material was obtained by isothermal drying at 40-60°C in a vacuum oven for 18-24 hours.
[0020] S6. Preparation of Eucalyptus-like Co-Fe2P@N-doped Carbon
[0021] The PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was loaded into a porcelain boat and then placed in a tube furnace. It was calcined at 500-700°C for 1-2 hours at a heating rate of 1-10°C / min under a nitrogen atmosphere, then heated to 920-1000°C and calcined for 1-5 hours. It was then cooled to room temperature under a nitrogen flow to obtain eucalyptus-like Co-Fe2P@nitrogen-doped carbon.
[0022] Preferably, the concentration of MoO3 in solution A is 0.0348 g / mL.
[0023] Preferably, the concentration of EDA in solution B is 0.0067 g / mL, the concentration of PMDA in solution C is 0.00884 g / mL, and the concentration of MoO3 in solution E is 0.001875 g / mL.
[0024] Preferably, the concentration of MoO3 / PI in solution F is 0.0015 g / mL, the concentration of zinc nitrate hexahydrate is 0.00223 g / mL, and the concentration of 2-methylimidazole is 0.00231 g / mL.
[0025] Preferably, the concentration of MoO3 / PI@ZIF-8 in solution G is 0.01 g / mL, and the concentration of phytic acid is 0.1 M.
[0026] Preferably, the concentration of the PI@ZIF-8 tube-sheet superstructure in solution H is 0.002 g / mL, the concentration of ferric nitrate nonahydrate is 0.0005 g / mL, and the concentration of cobalt nitrate hexahydrate is 0.0005 g / mL.
[0027] The second object of the present invention is to provide a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst prepared by the above preparation method.
[0028] The third object of the present invention is to provide an application of the above-mentioned eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst in aluminum-air batteries.
[0029] The present invention provides a method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst. The catalyst prepared by the method has a special eucalyptus structure. This structure has a higher specific surface area, so it can accommodate more active sites, and there is a local strong electric field nearby, which can increase the OH - concentration, which helps the adsorption and desorption process of oxygen intermediates and improves the electrocatalytic performance.
[0030] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:
[0031] 1) This eucalyptus-like structure boasts abundant internal and external surfaces, significantly increasing the catalyst's specific surface area. This allows more active sites to be exposed at the reaction interface, allowing for ample contact with the reactant oxygen, thereby increasing the rate of electrocatalytic ORR. The structure also exhibits excellent electron conductivity, with its porous structure enabling rapid electron transport within the material, effectively reducing energy loss during electron transport. Furthermore, this unique structure provides rapid transport pathways for oxygen and electrolyte ions, while enhancing the catalyst's chemical stability.
[0032] 2) The present invention utilizes a low-energy synthesis process, resulting in a simple preparation process requiring only stirring and heating. The resulting electrocatalyst exhibits high purity and excellent crystallization properties, with electrocatalytic activity significantly superior to commercial catalysts. This aluminum-air battery catalyst utilizes environmentally friendly, non-toxic raw materials and is prepared at low cost using a non-precious metal system. It exhibits excellent cycling stability and durability in aluminum-air battery applications, making it a highly efficient catalyst system that combines both economical efficiency and reliability.
[0033] 3) From the perspective of the catalyst structure, the catalyst of the present invention has a special eucalyptus structure, which has a higher specific surface area and can accommodate more active sites. In addition, there is a local strong electric field nearby, which can increase the OH - The concentration is conducive to the adsorption and desorption process of oxygen intermediates and improves the electrocatalytic performance. The catalyst has a nitrogen-doped carbon skeleton structure, and its excellent conductivity can effectively promote the mass transfer and charge transfer efficiency in the electrocatalytic reaction.
[0034] From the perspective of the catalyst's composition, Co-doped Fe2P is embedded in the NC matrix to form Fe-N atomic bridges, which optimize the local electronic structure of the Fe atoms. Furthermore, Co doping optimizes the structural model of the Co-Fe2P@NC catalyst, further promoting the adsorption and desorption of oxygen intermediates and accelerating the reaction kinetics, resulting in excellent electrocatalytic performance.
[0035] The performance of aluminum-air batteries (ALBs) demonstrates the long-term stability of the catalyst presented in this study compared to commercial Pt / C catalysts, demonstrating the structural integrity and degradation resistance of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst under continuous operation. It maintains high voltage and specific capacity, excellent rate capability over a wide current density range, and voltage recovery to its initial level after high-current cycling. Its high open-circuit voltage fully demonstrates the material's practical value in advanced energy devices.
[0036] 4) Doping and interface regulation are effective strategies for regulating the electrochemical performance of metal catalysts. This is because Co doping reconstructs the electronic structure of the catalyst and significantly reduces the adsorption / desorption energy barrier of oxygen intermediates. Importantly, the Co-Fe2P site is attached to the NC substrate through Fe-N bonds, generating an atomic bridge interface. This interface provides a favorable pathway for high-speed charge transfer and significantly improves the electrocatalytic performance. This preparation method adopts the strategy of loading Co-doped Fe2P on a eucalyptus carbon substrate, which not only fully exposes the active sites to promote mass transfer and charge transfer in the electrocatalytic process, but also utilizes the local strong electric field formed on the surface to achieve OH - This synergistic effect can significantly reduce the adsorption / desorption energy barrier of reaction intermediates at the active site, thereby ultimately improving the electrocatalytic performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0038] Figure 1 This is a morphological diagram of the Eucalyptus plant;
[0039] Figure 2 The electrostatic field distribution on the surface of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst structure model obtained using the finite element method;
[0040] Figure 3 The OH- concentration distribution on the surface of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst structure model obtained using the finite element method;
[0041] Figure 4 Flow chart for the preparation of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0042] Figure 5 This is a scanning electron microscopy image of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0043] Figure 6 Transmission electron microscopy image of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0044] Figure 7 High-resolution transmission electron microscopy image of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0045] Figure 8 is the C signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0046] Figure 9 is the N signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0047] Figure 10 is the P signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0048] Figure 11 is the Co signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0049] Figure 12 is the Fe signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst;
[0050] Figure 13 Polarization and power density curves of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and Pt / C catalyst;
[0051] Figure 14 Energy density and specific capacity evaluation of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalysts, as well as energy density and specific capacity evaluation of Pt / C catalysts;
[0052] Figure 15 The discharge curves of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and the discharge curves of the Pt / C catalyst. DETAILED DESCRIPTION
[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0054] Example 1
[0055] This embodiment provides a method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst, which specifically includes the following steps:
[0056] Preparation of S1 and MoO3
[0057] 2.0 g of ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 4H2O) was dissolved in a mixture of 9.5 mL of concentrated nitric acid (68%) and 48 mL of deionized water, and magnetically stirred at room temperature for 20 minutes to form precursor solution A1. The precursor suspension was injected into a 100 mL polytetrafluoroethylene-lined autoclave and hydrothermally treated at 180°C for 24 hours. After the system cooled naturally to room temperature, the white product was collected by centrifugation, washed three times with alternating deionized water and ethanol, and then dried in a vacuum oven at 60°C for 18 hours to produce MoO3 nanorods.
[0058] Preparation of S2, MoO3 / PI
[0059] 96 mg of ethylenediamine (EDA) was dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution B1. 353.6 mg of pyromellitic dianhydride (PMDA) was dissolved in 20 mL of DMF to obtain solution C1. Solutions B1 and C1 were thoroughly mixed and magnetically stirred at room temperature for 6 hours to form a transparent polyamic acid (PAA) prepolymer solution. After dilution with 130 mL of DMF, mechanical stirring was continued for 10 minutes to obtain a homogeneous system, obtaining solution D1. Molybdenum trioxide nanorods were ultrasonically dispersed in 160 mL of DMF to prepare a stable suspension, obtaining solution E1. The two-phase system was thoroughly mixed and transferred to a 500 mL two-necked round-bottom flask equipped with a mechanical stirrer. A temperature gradient polymerization reaction was carried out in a 150°C oil bath, maintaining vigorous reflux and stirring for 1 hour to complete the polymerization process. After the reaction was terminated, the product was separated by high-speed centrifugation, washed three times with DMF-ethanol alternatingly, and then dried in a vacuum drying oven at 60°C for 12 h to obtain MoO3 / polyimide (MoO3 / PI) nanocomposite material;
[0060] Preparation of S3, MoO3 / PI@ZIF-8
[0061] 120 mg of MoO₃ / PI and 178.5 mg of zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) were dissolved in 80 mL of methanol and stirred for 3 hours. Next, 184.8 mg of 2-methylimidazole was added to the solution. After stirring for 0.5 hours, the solution was allowed to stand for 24 hours to obtain Solution F1. The resulting product was then washed and dried at 60°C for 18 hours.
[0062] S4. Preparation of PI@ZIF-8 tube-sheet superstructure
[0063] 200 mg of MoO3 / PI@ZIF-8 was dispersed in 20 mL of ultrapure water to obtain solution G1. Subsequently, 30 mL of 0.1 M phytic acid was added to the solution, and the mixture was allowed to react at 90°C for 3 hours. After the reaction, the resulting product was washed and then dried at 60°C for 18 hours, resulting in a PI@ZIF-8 tube-sheet superstructure.
[0064] S5. Preparation of PI@ZIF-8 tube-sheet superstructures with adsorption of cobalt and iron ions
[0065] 60 mg of the PI@ZIF-8 tube-sheet superstructure was weighed as the support matrix and dissolved in 30 mL of methanol solvent with 15 mg of ferric nitrate nonahydrate (Fe(NO₃)₃·9H₂O) and 15 mg of cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) as bimetallic precursors. This solution, H1, was dispersed by magnetic stirring and aged at room temperature for 24 hours. The composite precipitate was obtained by centrifugation and washed with alternating methanol / deionized water to remove unreacted products. Finally, the PI@ZIF-8 tube-sheet superstructure, adsorbed with cobalt and iron ions, was obtained by drying at 60°C in a vacuum oven for 18 hours.
[0066] S6. Preparation of Eucalyptus-like Co-Fe2P@N-doped Carbon Electrocatalyst
[0067] The PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was loaded into a porcelain boat and then placed in a tubular furnace. It was calcined at 600°C for 1 hour at a heating rate of 3°C / min under a nitrogen atmosphere, then heated to 950°C and calcined for 2 hours. It was then cooled to room temperature under a nitrogen flow to obtain the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst.
[0068] Figure 1 This is a photo of a eucalyptus plant.
[0069] Figure 2This is the electrostatic field distribution diagram of the surface of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst structure model. This eucalyptus-like structure has a strong spatial average electric field strength (127580V / m). The enhanced electric field is beneficial to the ORR-related substances (OH - , K + and O2) accumulation, while OH adsorbed on the surface of the eucalyptus-like structure - It can transfer electrons to the catalyst site, promote the adsorption and activation of O2, and improve the ORR catalytic activity.
[0070] Figure 3 The OH on the surface of the Eucalyptus-like Co-Fe2P@ nitrogen-doped carbon electrocatalyst structure model - Concentration distribution diagram of OH around the surface of this eucalyptus-like structure - The concentration is much higher than that of OH around the cylindrical structure. - concentration, which is due to OH - Electrostatic adsorption between the anode and the OH adsorbed on the surface of the eucalyptus-like structure - It can transfer electrons to the catalyst site, promote the adsorption and activation of O2, and improve the ORR catalytic activity.
[0071] Figure 4 This is the preparation process of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst.
[0072] Figure 5 This is a scanning electron microscope image of the eucalyptus-like Co-Fe2P@ nitrogen-doped carbon electrocatalyst. Figure 5 The catalyst exhibits a hollow, eucalyptus-like structure, which has abundant internal and external surfaces, significantly increasing the catalyst's specific surface area.
[0073] Figure 6 This is a transmission electron microscope image of the eucalyptus-like Co-Fe2P@ nitrogen-doped carbon electrocatalyst. Figure 6 The product exhibits a hollow, eucalyptus-like structure, which exposes more active sites at the reaction interface and allows for sufficient contact with the reactant oxygen, thereby enhancing the electrocatalytic rate. This structure also exhibits excellent electron conductivity, with its hierarchical porous structure enabling rapid electron transport within the material, effectively reducing energy loss during electron transport. Furthermore, this unique structure provides rapid transport pathways for oxygen and electrolyte ions, while enhancing the chemical stability of the catalyst.
[0074] Figure 7 This is a high-resolution transmission electron microscopy image of the eucalyptus-like Co-Fe2P@ nitrogen-doped carbon electrocatalyst. Figure 7The HRTEM image and the corresponding inverse Fourier transform (IFFT) map confirm the presence of the Fe2P lattice phase. The lattice fringe spacing is 0.2073 nm, highlighting the unique characteristics of the (201) crystal plane of Fe2P. It is also observed that the external graphitic carbon protects the catalytic center from electrolyte corrosion.
[0075] Figure 8 The C signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst is shown. The C 1s spectrum exhibits peaks at 284.4 eV, 285.9 eV, and 286.6 eV, corresponding to C-C / C=C, C-N, and C-O bonds, respectively. The presence of CN species confirms the effective nitrogen doping of the carbon matrix and provides strong evidence for the construction of nitrogen-doped carbonaceous structures.
[0076] Figure 9 The N signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst is shown. The N 1s spectrum displays multiple peaks at 398.1eV (pyridinic nitrogen), 399.1eV (MN), 400.3eV (pyrrolic nitrogen), and 401.4eV (graphitic nitrogen). The MN signal indicates the presence of chemical bonds between Fe and N atoms, ensuring the strong anchoring of the Fe2P component to the carbon substrate. Furthermore, the pyridinic, pyrrolic, and graphitic nitrogen species effectively enhance the electrocatalyst's conductivity, accelerating charge transport.
[0077] Figure 10 This is the P signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst. The P 2p spectrum can be decomposed into three distinct signals with binding energies of 129.4 eV, 130.3 eV (MP bond), and 133.5 eV (PO bond). The prominent MP peak indicates the formation of the Fe2P phase.
[0078] Figure 11 is the Co signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst; multiple splitting signals were observed at 780.6 / 795.8eV, 782.3 / 797.3eV and 786.0 / 803.3eV, corresponding to Co 3+ 、Co 2+ and its satellite peaks, proving the presence of Co components in the catalyst.
[0079] Figure 12 is the Fe signal in the X-ray photoelectron spectrum of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst; Fe-P (707.5eV and 720.2eV), Fe-N (709.0eV and 722.0eV), Fe 2+ (711.2eV and 724.0eV), Fe3+ (713.7 eV and 727.0 eV) and a pair of satellite peaks located at 717.3 eV and 730.7 eV, which proves the presence of Fe component in the catalyst.
[0080] Figure 13 The polarization and power density curves of Eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and commercial precious metal Pt / C are shown in Figure 2. The polarization curve and power density analysis show that the product of Eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst has a power density of 252 mA / cm 2 The current density reaches 258mW / cm 2 The peak power density is significantly better than that of Pt / C catalyst (212mW / cm 2 ).
[0081] Figure 14 This is an evaluation diagram of the energy density and specific capacity of eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and commercial precious metal Pt / C; Eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst at 120mA / cm 2 At the same current density, the electrode can maintain high voltage and specific capacity during constant current discharge for 2 hours. Specifically, the electrode achieves a specific capacity of 2491mAh / g and an energy density of 3487Wh / kg, far exceeding the 2170mAh / g and 2192Wh / kg of the Pt / C catalyst.
[0082] Figure 15 This is the discharge curve of Eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst and commercial precious metal Pt / C. As can be seen from the figure, the battery assembled with Eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst also shows excellent cycle stability at 25mA / cm 2 After 160 hours of discharge at the same current density, even after three replacements of the aluminum anode, the voltage retention rate is still higher than 95%, which is better than the precious metal Pt / C.
[0083] Example 2
[0084] This embodiment provides a method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst, which specifically includes the following steps:
[0085] Preparation of S1 and MoO3
[0086] 2.0 g of ammonium molybdate tetrahydrate ((NH4)6Mo7O 244H2O) was dissolved in a mixture of 9.5 mL of concentrated nitric acid (68%) and 48 mL of deionized water, and magnetically stirred at room temperature for 20 minutes to form precursor solution A2. The precursor suspension was injected into a 100 mL polytetrafluoroethylene-lined autoclave and hydrothermally treated at 180°C for 24 hours. After the system cooled naturally to room temperature, the white product was collected by centrifugation, washed three times with alternating deionized water and ethanol, and then dried in a vacuum oven at 60°C for 18 hours to produce MoO3 nanorods.
[0087] Preparation of S2, MoO3 / PI
[0088] 96 mg of ethylenediamine (EDA) was dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution B2. 353.6 mg of pyromellitic dianhydride (PMDA) was dissolved in 20 mL of DMF to obtain solution C2. Solutions B2 and C2 were thoroughly mixed and magnetically stirred at room temperature for 6 hours to form a transparent polyamic acid (PAA) prepolymer solution. After dilution with 130 mL of DMF, mechanical stirring was continued for 10 minutes to obtain a homogeneous system, obtaining solution D2. Molybdenum trioxide nanorods were ultrasonically dispersed in 160 mL of DMF to prepare a stable suspension, obtaining solution E2. The two-phase system was thoroughly mixed and transferred to a 500 mL two-necked round-bottom flask equipped with a mechanical stirrer. A temperature gradient polymerization reaction was carried out in a 155°C oil bath, maintaining vigorous reflux and stirring for 1 hour to complete the polymerization process. After the reaction was terminated, the product was separated by high-speed centrifugation, washed three times with DMF-ethanol alternatingly, and then dried in a vacuum drying oven at 60°C for 12 h to obtain MoO3 / polyimide (MoO3 / PI) nanocomposite material;
[0089] Preparation of S3, MoO3 / PI@ZIF-8
[0090] 120 mg of MoO3 / PI and 178.5 mg of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in 80 mL of methanol and stirred for 3 hours. Next, 184.8 mg of 2-methylimidazole was added to the solution. After stirring for 0.5 hours, the solution was allowed to stand for 24 hours to obtain solution F2. The resulting product was then washed and dried at 60°C for 18 hours to obtain MoO3 / PI@ZIF-8.
[0091] S4. Preparation of PI@ZIF-8 tube-sheet superstructure
[0092] 200 mg of MoO3 / PI@ZIF-8 was dispersed in 20 mL of ultrapure water to obtain solution G2. Subsequently, 30 mL of 0.1 M phytic acid was added to the system, and the mixture was allowed to react at 90°C for 3 hours. After the reaction was complete, the resulting product was washed and then dried at 60°C for 18 hours.
[0093] S5. Preparation of PI@ZIF-8 tube-sheet superstructures with adsorption of cobalt and iron ions
[0094] 60 mg of the PI@ZIF-8 tube-sheet superstructure was weighed as the support matrix and dissolved in 30 mL of methanol solvent with 30 mg of ferric nitrate nonahydrate (Fe(NO₃)₃·9H₂O) and 15 mg of cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) as bimetallic precursors. This solution, H2, was dispersed by magnetic stirring and then aged at room temperature for 24 hours. The composite precipitate was obtained by centrifugation and washed with alternating methanol / deionized water to remove unreacted products. Finally, the PI@ZIF-8 tube-sheet superstructure, adsorbed with cobalt and iron ions, was obtained by drying at 60°C in a vacuum oven for 18 hours.
[0095] S6. Preparation of Eucalyptus-like Co-Fe2P@N-doped Carbon Electrocatalyst
[0096] The PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was loaded into a porcelain boat and then placed in a tubular furnace. It was calcined at 600°C for 1 hour at a heating rate of 3°C / min under a nitrogen atmosphere, then heated to 950°C and calcined for 2 hours. It was then cooled to room temperature under a nitrogen flow to obtain the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst.
[0097] Example 3
[0098] This embodiment provides a method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst, which specifically includes the following steps:
[0099] Preparation of S1 and MoO3
[0100] 2.0 g of ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 4H2O) was dissolved in a mixture of 9.5 mL of concentrated nitric acid (68%) and 48 mL of deionized water, and magnetically stirred at room temperature for 20 minutes to form precursor solution A3. The precursor suspension was injected into a 100 mL polytetrafluoroethylene-lined autoclave and hydrothermally treated at 180°C for 24 hours. After the system cooled naturally to room temperature, the white product was collected by centrifugation, washed three times with alternating deionized water and ethanol, and then dried in a vacuum oven at 60°C for 18 hours to produce MoO3 nanorods.
[0101] Preparation of S2, MoO3 / PI
[0102] 96 mg of ethylenediamine (EDA) was dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution B3. 353.6 mg of pyromellitic dianhydride (PMDA) was dissolved in 20 mL of DMF to obtain solution C3. Solutions B3 and C3 were thoroughly mixed and magnetically stirred at room temperature for 6 hours to form a transparent polyamic acid (PAA) prepolymer solution. After dilution with 130 mL of DMF, mechanical stirring was continued for 10 minutes to obtain a homogeneous system, obtaining solution D3. Molybdenum trioxide nanorods were ultrasonically dispersed in 160 mL of DMF to prepare a stable suspension, obtaining solution E3. The two-phase system was thoroughly mixed and transferred to a 500 mL two-necked round-bottom flask equipped with a mechanical stirrer. A gradient temperature polymerization reaction was carried out in an oil bath at 145-165°C, maintaining vigorous reflux and stirring for 1 hour to complete the polymerization process. After the reaction was terminated, the product was separated by high-speed centrifugation, washed three times with DMF-ethanol alternatingly, and then dried in a vacuum drying oven at 60°C for 12 h to obtain MoO3 / polyimide (MoO3 / PI) nanocomposite material;
[0103] Preparation of S3, MoO3 / PI@ZIF-8
[0104] 120 mg of MoO3 / PI and 178.5 mg of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in 80 mL of methanol and stirred for 3 hours. Next, 184.8 mg of 2-methylimidazole was added to the solution. After stirring for 0.5 hours, the solution was allowed to stand for 24 hours, yielding Solution F3. The resulting product was then washed and dried at 60°C for 18 hours to obtain MoO3 / PI@ZIF-8.
[0105] S4. Preparation of PI@ZIF-8 tube-sheet superstructure
[0106] 200 mg of MoO3 / PI@ZIF-8 was dispersed in 20 mL of ultrapure water to obtain solution G3. Subsequently, 30 mL of 0.1 M phytic acid was added to the system, and the mixture was allowed to react at 90°C for 3 hours. After the reaction was complete, the resulting product was washed and then dried at 60°C for 18 hours.
[0107] S5. Preparation of PI@ZIF-8 tube-sheet superstructures with adsorption of cobalt and iron ions
[0108] 60 mg of the PI@ZIF-8 tube-sheet superstructure was weighed as the support matrix and dissolved in 30 mL of methanol solvent with 15 mg of ferric nitrate nonahydrate (Fe(NO₃)₃·9H₂O) and 30 mg of cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) as bimetallic precursors. This solution, H3, was dispersed by magnetic stirring and then aged at room temperature for 24 hours. The composite precipitate was obtained by centrifugation and washed with alternating methanol / deionized water to remove unreacted products. Finally, the PI@ZIF-8 tube-sheet superstructure, adsorbed with cobalt and iron ions, was obtained by drying at 60°C in a vacuum oven for 18 hours.
[0109] S6. Preparation of Eucalyptus-like Co-Fe2P@N-doped Carbon Electrocatalyst
[0110] The PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was loaded into a porcelain boat and then placed in a tubular furnace. It was calcined at 600°C for 1 hour at a heating rate of 3°C / min under a nitrogen atmosphere, then heated to 950°C and calcined for 2 hours. It was then cooled to room temperature under a nitrogen flow to obtain the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst.
[0111] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.
[0112] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a eucalyptus-like Co-Fe2P@ nitrogen-doped carbon electrocatalyst, characterized in that: The steps include: Preparation of S1 and MoO3 Dissolve ammonium molybdate tetrahydrate in a mixture of concentrated nitric acid and deionized water, and stir to obtain a precursor solution A; The precursor solution A was injected into the reactor and subjected to hydrothermal treatment. After the system was naturally cooled to room temperature, the white product was collected by centrifugation, washed and dried to obtain MoO3 nanorods. Preparation of S2, MoO3 / PI Dispersing ethylenediamine in a solvent to obtain solution B; dissolving pyromellitic dianhydride in a solvent to obtain solution C; thoroughly mixing solutions B and C, stirring to form a transparent polyamic acid solution, and then diluting with a solvent and continuing to stir to obtain a homogeneous system to obtain solution D; ultrasonically dispersing MoO3 nanorods in a solvent to prepare a stable suspension to obtain solution E; Solution D and solution E were fully mixed and transferred to a container, and a gradient temperature polymerization reaction was carried out in an oil bath at 145-165°C. Vigorous reflux stirring was maintained for 1-2 hours to complete the polymerization process. After the reaction was terminated, the product was separated by high-speed centrifugation, washed, and dried to obtain MoO3 / PI; Preparation of S3, MoO3 / PI@ZIF-8 MoO3 / PI and zinc nitrate hexahydrate were dissolved in a methanol solution and stirred for 3-5 hours. 2-Methylimidazole was then added to the solution and stirred for 0.5-2 hours to obtain a solution F. The solution was allowed to stand for 18-24 hours. The final product was then washed and dried to obtain MoO3 / PI@ZIF-8. S4. Preparation of PI@ZIF-8 tube-sheet superstructure MoO3 / PI@ZIF-8 was dispersed in ultrapure water to obtain solution G, and then phytic acid was added to the system. The system was then reacted at 80-100°C for 3-5 hours. After the reaction was completed, the generated product was washed and dried to obtain the PI@ZIF-8 tube-sheet superstructure. S5. Preparation of PI@ZIF-8 tube-sheet superstructures with adsorption of cobalt and iron ions The PI@ZIF-8 tube-sheet superstructure was weighed as a carrier matrix and co-dissolved with bimetallic precursors of ferric nitrate nonahydrate and cobalt nitrate hexahydrate in a methanol solvent system to obtain solution H. After dispersion by magnetic stirring, the solution was allowed to stand and age at room temperature for 18-24 hours to complete structural self-assembly. The composite precipitate was obtained by centrifugation, and the PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was obtained after washing and drying. S6. Preparation of Eucalyptus-like Co-Fe2P@N-doped Carbon The PI@ZIF-8 tube-sheet superstructure adsorbing cobalt and iron ions was loaded into a porcelain boat and then placed in a tube furnace for calcination. It was then cooled to room temperature under a nitrogen flow to obtain a eucalyptus-like Co-doped Fe2P@nitrogen-doped carbon composite catalytic material.
2. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S1, the concentration of ammonium molybdate tetrahydrate in solution A is 0.00348-0.0348 g / mL; the volume fraction of concentrated nitric acid is 68%; concentrated nitric acid and deionized water are mixed in a volume ratio of (0.1-0.3):1; hydrothermal treatment is performed at 160-200° C. for 18-24 hours; and drying is performed at 40-60° C. for 12-18 hours.
3. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S2, the concentration of ethylenediamine in solution B is 0.002-0.02 g / mL; the concentration of pyromellitic dianhydride in solution C is 0.006-0.06 g / mL; the volume ratio of solution B to solution C is 1:1; the concentration of MoO3 nanorods in solution E is 0.001-0.01 g / mL; the volume ratio of solution D to solution E is 1:1.2; and the drying is performed at 40-60°C for 12-18 hours.
4. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S3, the concentration of MoO3 / PI in solution F is 0.001-0.01 g / mL, the concentration of zinc nitrate hexahydrate is 0.002-0.02 g / mL, and the concentration of 2-methylimidazole is 0.002-0.02 g / mL; and the drying step is performed at 40-60°C for 18-24 hours.
5. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S4, the concentration of MoO3 / PI@ZIF-8 in solution G is 0.01-0.1 g / mL; the concentration of phytic acid is 0.1-1.0 M; and the drying step is performed at 40-60°C for 18-24 hours.
6. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S5, the concentration of the PI@ZIF-8 tube-sheet superstructure in solution H is 0.002-0.02 g / mL, the concentration of ferric nitrate nonahydrate is 0.0005-0.005 g / mL, and the concentration of cobalt nitrate hexahydrate is 0.0005-0.005 g / mL; and the drying step is performed at 40-60° C. for 18-24 hours.
7. The method for preparing a eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that: In step S6, the calcination is carried out under a nitrogen atmosphere at a temperature of 500-700° C. for 1-2 hours at a heating rate of 1-10° C. / min, and then the temperature is raised to 920-1000° C. for 1-5 hours.
8. A eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst prepared by the preparation method of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst according to any one of claims 1 to 7.
9. Application of the eucalyptus-like Co-Fe2P@nitrogen-doped carbon electrocatalyst as described in 8 in aluminum-air batteries.