A method for preparing an asymmetrically coordinated iron single atom catalyst
By preparing asymmetric coordinated iron single-atom catalysts, the problems of polyiodide shuttle effect and slow iodine conversion kinetics in zinc-iodine batteries were solved, achieving efficient electronic coupling and improved reaction kinetics of the catalysts, and significantly improving the cycle stability and rate performance of zinc-iodine batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG WANLI UNIV
- Filing Date
- 2026-01-08
- Publication Date
- 2026-06-02
Smart Images
Figure CN122136362A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of energy storage materials technology, specifically relating to a method for preparing an asymmetric coordinated iron single-atom catalyst. Background Technology
[0002] With the rapid development of the sustainable energy industry, the demand for safe, efficient, and low-cost energy storage systems is becoming increasingly urgent. Aqueous zinc-iodine batteries (AZIBs) have become a strong candidate for next-generation energy storage systems due to their high safety, environmental friendliness, and low cost. However, the practical application of zinc-iodine batteries still faces severe challenges: on the one hand, the polyiodide shuttle effect leads to the loss of active materials and severe self-discharge; on the other hand, the slow kinetics of the iodine redox reaction limits the rate performance and cycle life of the battery. Although traditional carbon-based materials (such as porous carbon, carbon nanotubes, and graphene) can suppress polyiodide diffusion through physical confinement, their non-polar surfaces have weak interactions with polyiodides, making it impossible to fundamentally solve the shuttle effect. Single-atom catalysts (SACs) have shown great potential in improving the kinetics of iodine reduction reactions due to their extremely high atom utilization and unique electronic structure. Among them, iron-based single-atom catalysts (Fe-SACs) have attracted widespread attention due to their tunable coordination environment. However, traditional symmetrical Fe-N4 structured single-atom catalysts suffer from problems such as high intermediate adsorption energy barriers and single reaction pathways, limiting their catalytic performance. Studies have shown that the spin state of the central metal atom is a key electronic descriptor that determines catalytic activity. By controlling the spin state through regulation of the coordination environment, the interaction between the electronic structure and reaction intermediates can be optimized.
[0003] Therefore, designing asymmetric coordinated iron single-atom catalysts with specific spin states has become the core idea for solving the existing defects of zinc-iodine batteries. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies and address the problems of severe polyiodide shuttle effect, slow iodine conversion kinetics, and insufficient catalytic performance of traditional single-atom catalysts in current zinc-iodine batteries, this invention provides an asymmetric coordinated iron single-atom catalyst. By precisely controlling the coordination environment and spin state of the Fe center, the catalytic activity and stability are enhanced. It exhibits high specific capacitance, excellent rate performance, and good cycle stability.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for preparing an asymmetric coordinated iron single-atom catalyst involves using polystyrene as a template, modifying and coating it with dopamine, and using FeCl3, thiourea, and hexachlorotriphosphazene as precursors for Fe, S, and P to prepare a PS@PDA-FeSP precursor. The asymmetric coordinated iron single-atom catalyst is obtained by high-temperature decomposition of the PS@PDA-FeSP precursor using a template-assisted method.
[0007] Preferably, the preparation method specifically includes the following steps:
[0008] (1) Preparation of precursor dispersion: Polystyrene microspheres were dispersed in water and ultrasonically dispersed. Then, dopamine, FeCl3, thiourea and hexachlorotriphosphazene were added in sequence and ultrasonically dispersed again to obtain a uniform mixture.
[0009] (2) In-situ polymerization reaction: The mixture obtained in step (1) is reacted under heating and stirring conditions to form a polydopamine coating layer by in-situ oxidative polymerization of dopamine, and Fe, S and P precursors are loaded simultaneously. After the reaction is completed, the mixture is separated by solid and liquid, washed and dried to obtain PS@PDA-FeSP precursor.
[0010] (3) High-temperature pyrolysis: The PS@PDA-FeSP precursor obtained in step (2) is subjected to programmed temperature rise heat treatment under inert atmosphere protection, and then cooled to obtain the catalyst.
[0011] Preferably, in step (1), the mass ratio of the polystyrene microspheres, dopamine, FeCl3, thiourea and hexachlorotriphosphazene is 1:1~2:0.2~0.6:0.6~1.2:0.4~0.8.
[0012] Most preferably, the mass ratio of polystyrene microspheres, dopamine, FeCl3, thiourea, and hexachlorotriphosphazene is 1.0 g: 1.0 g: 0.2 g: 0.6 g: 0.4 g.
[0013] Preferably, in step (1), the ultrasonic dispersion time is 30-60 min; the continued ultrasonic dispersion time is 30-60 min.
[0014] Preferably, in step (2), the reaction temperature is 45~60℃ and the time is 15~18 h.
[0015] Preferably, in step (2), the solid-liquid separation is centrifugal separation; the washing is performed three times with deionized water; and the drying is performed under vacuum at 50-60°C for 10-12 hours.
[0016] Preferably, in step (3), the inert atmosphere is a nitrogen atmosphere and the gas flow rate is 40~60 mL / min.
[0017] Preferably, in step (3), the heating rate of the programmed heating heat treatment is 8 ℃ / min, the final temperature is 850 ℃, and the temperature is maintained at the final temperature for 2~3 h.
[0018] This invention also protects the asymmetric coordinated iron single-atom catalyst prepared by the method.
[0019] Furthermore, this invention also protects the application of the aforementioned asymmetric coordinated iron single-atom catalyst in the preparation of zinc-iodine battery cathodes.
[0020] Compared with the prior art, the beneficial effects of the present invention are:
[0021] The asymmetric coordinated iron single-atom catalyst prepared by the method provided in this invention breaks the symmetry of the traditional Fe-N4 structure, induces the formation of medium-to-low spin states at the Fe center, and optimizes the hybridization effect of the Fe 3d orbital and the p orbital of the iodine species (e.g., Figures 5 to 7 This significantly enhances electronic coupling and the adsorption and activation capabilities of polyiodides. The hollow carbon sphere structure of this catalyst provides a high specific surface area and abundant mesopores, offering ample confinement space and reaction interfaces for iodine species, thus significantly improving reaction kinetics. Attached Figure Description
[0022] Figure 1 This is a scanning electron microscope image of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0023] Figure 2 This is a transmission scanning electron microscope image of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0024] Figure 3 This is an elemental distribution diagram of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0025] Figure 4 This is a Fourier transform X-ray absorption spectrum of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0026] Figure 5 This is an X-ray photoelectron spectrum of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0027] Figure 6 This is a temperature-varying magnetic susceptibility diagram of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0028] Figure 7 This is a calculation plot of the Gibbs free energy of an asymmetric coordinated iron single-atom catalyst obtained in the examples;
[0029] Figure 8This is an electron scan image of the zinc anode surface of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst in the embodiments;
[0030] Figure 9 This is a coulombic efficiency diagram of the zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst in the examples;
[0031] Figure 10 This is a constant current charge-discharge diagram of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst in the embodiment.
[0032] Figure 11 This is a cyclic voltammetry curve of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst in the examples;
[0033] Figure 12 This is a curved cut view of the zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst in the embodiment. Detailed Implementation
[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments of the present invention are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.
[0035] Example 1
[0036] A method for preparing an asymmetric coordinated iron single-atom catalyst, comprising the following steps:
[0037] (1) Preparation of precursor dispersion: Weigh 1.0 g polystyrene (PS) microspheres and disperse them in 100 mL of deionized water. Disperse by ultrasonication for 30 min. Add 1.5 g dopamine, 0.4 g FeCl3, 0.9 g thiourea and 0.6 g hexachlorotriphosphazene in sequence and continue ultrasonic dispersion for 1 h to obtain a uniform mixture.
[0038] (2) In-situ polymerization reaction: The mixture was transferred to a 50℃ constant temperature water bath and mechanically stirred for 18 h. Dopamine was oxidized and polymerized in situ to form a PDA coating layer. Fe, S and P precursors were loaded simultaneously. After the reaction was completed, the mixture was separated by centrifugation, washed three times with deionized water, and vacuum dried at 60℃ for 12 h to obtain PS@PDA-FeSP precursor.
[0039] (3) High-temperature pyrolysis: The precursor was placed in a tube furnace and nitrogen gas was introduced (flow rate 50 mL / min). The temperature was increased to 850℃ at a rate of 8℃ / min, held for 3 h, and then naturally cooled to room temperature to obtain the FeSA-N2PS catalyst.
[0040] The catalyst was used to assemble a zinc-iodine battery with iodine as the positive electrode, zinc sheet as the negative electrode, glass fiber as the separator, and zinc sulfate as the electrolyte.
[0041] Example 2
[0042] A method for preparing an asymmetric coordinated iron single-atom catalyst, comprising the following steps:
[0043] (1) Preparation of precursor dispersion: Weigh 1.0 g polystyrene (PS) microspheres and disperse them in 100 mL of deionized water. Disperse by ultrasonication for 30 min. Add 2.0 g dopamine, 0.6 g FeCl3, 1.2 g thiourea and 0.8 g hexachlorotriphosphazene in sequence and continue ultrasonic dispersion for 1 h to obtain a uniform mixture.
[0044] (2) In-situ polymerization reaction: The mixture was transferred to a 50℃ constant temperature water bath and mechanically stirred for 18 h. Dopamine was oxidized and polymerized in situ to form a PDA coating layer. Fe, S and P precursors were loaded simultaneously. After the reaction was completed, the mixture was separated by centrifugation, washed three times with deionized water, and vacuum dried at 60℃ for 12 h to obtain PS@PDA-FeSP precursor.
[0045] (3) High-temperature pyrolysis: The precursor was placed in a tube furnace and nitrogen gas was introduced (flow rate 50 mL / min). The temperature was increased to 850℃ at a rate of 8℃ / min, held for 3 h, and then naturally cooled to room temperature to obtain the FeSA-N2PS catalyst.
[0046] The catalyst was used to assemble a zinc-iodine battery with iodine as the positive electrode, zinc sheet as the negative electrode, glass fiber as the separator, and zinc sulfate as the electrolyte.
[0047] Example 3
[0048] A method for preparing an asymmetric coordinated iron single-atom catalyst, comprising the following steps:
[0049] (1) Preparation of precursor dispersion: Weigh 1.0 g polystyrene (PS) microspheres and disperse them in 100 mL of deionized water. Disperse by ultrasonication for 30 min. Add 1.0 g dopamine, 0.2 g FeCl3, 0.6 g thiourea and 0.4 g hexachlorotriphosphazene in sequence and continue ultrasonic dispersion for 1 h to obtain a uniform mixture.
[0050] (2) In-situ polymerization reaction: The mixture was transferred to a 50℃ constant temperature water bath and mechanically stirred for 18 h. Dopamine was oxidized and polymerized in situ to form a PDA coating layer. Fe, S and P precursors were loaded simultaneously. After the reaction was completed, the mixture was separated by centrifugation, washed three times with deionized water, and vacuum dried at 60℃ for 12 h to obtain PS@PDA-FeSP precursor.
[0051] (3) High-temperature pyrolysis: The precursor was placed in a tube furnace and nitrogen gas was introduced (flow rate 50 mL / min). The temperature was increased to 850℃ at a rate of 8℃ / min, held for 3 h, and then naturally cooled to room temperature to obtain the FeSA-N2PS catalyst.
[0052] (4) A zinc-iodine battery was assembled using the catalyst with iodine as the positive electrode, zinc sheet as the negative electrode, glass fiber as the separator, and zinc sulfate as the electrolyte.
[0053] Figure 1 This is a scanning electron microscope image of an asymmetric coordinated iron single-atom catalyst. As can be seen from the image, the iron single-atom catalyst atoms are uniformly distributed and neatly arranged.
[0054] Figure 2 This is a transmission scanning electron microscope image of an asymmetric coordinated iron single-atom catalyst. As can be seen from the image, the iron single-atom catalyst atoms all exhibit a regular hollow spherical morphology and are uniform in size.
[0055] Figure 3 This is an elemental distribution diagram of an asymmetric coordinated iron single-atom catalyst. The diagram shows that C, N, P, S, and Fe are uniformly distributed in the synthesized solid electrolyte. The elemental distribution is highly uniform, and the signals of P and S highly coincide with the positions of the Fe sites, preliminarily indicating the successful preparation of the FeSA-N2PS catalyst.
[0056] Figure 4 This is a Fourier transform X-ray absorption spectrum of an asymmetrically coordinated iron single-atom catalyst. Wavelet transform analysis further verified the coordination environment of Fe, and the results showed that the Fe atoms in FeSA-N2PS, FeSA-N3S, and FeSA-N3P all exhibit typical Fe-N coordination characteristics.
[0057] Figure 5 This is an X-ray photoelectron spectroscopy (XPS) spectrum of an asymmetric coordinated iron single-atom catalyst. XPS analysis confirmed the crucial roles of P and S in fine-tuning the chemical state of the Fe center. The results showed that the Fe atoms in FeSA-N2PS, FeSA-N3S, and FeSA-N3P did not exist in a metallic state, but only in an oxidized state, with FeSA-N2PS exhibiting the highest oxidation state.
[0058] Figure 6This is a temperature-dependent magnetic susceptibility (TSS) curve for an asymmetric coordinated iron single-atom catalyst. The TSS test verifies the spin-state characteristics of the Fe center. The results show that the synergistic doping of P and S breaks the symmetry of the traditional Fe-N4 structure. Through the synergistic effect of the strong-field ligand (P) and the weak-field ligand (S), the crystal field splitting energy (Δ) is finely controlled, thereby affecting the electron configuration of the Fe 3d orbitals.
[0059] Figure 7 This is a Gibbs free energy calculation for an asymmetric coordinated iron single-atom catalyst. The Gibbs free energy calculation verifies that the P and S dual doping-induced low-spin FeSA-N2PS promotes dp orbital hybridization and charge transfer, optimizing the hybridization effect between Fe 3d orbitals and iodine species p orbitals. The calculation results show that FeSA-N2PS exhibits the lowest energy barrier in the I2 reduction pathway, demonstrating optimal reaction thermodynamic properties and significantly improving its adsorption and catalytic conversion performance for polyiodides.
[0060] Figure 8 This is an electron scanning image of the zinc anode surface in a zinc-iodine battery assembled using an asymmetrically coordinated iron single-atom catalyst. The zinc anode surface is smooth and free of cracks, effectively protecting the zinc anode and improving the battery's cycle stability.
[0061] Figure 9 The figure shows the coulombic efficiency of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst. As can be seen from the figure, at a 50C rate, the battery maintains a coulombic efficiency of 99.5% after 100,000 cycles, demonstrating extremely strong cycle stability.
[0062] Figure 10 The figure shows the galvanostatic charge-discharge curve of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst. It can be seen from the figure that the discharge capacity reaches 216.98 Ah·g at 0.2C. -1 It has excellent rate performance.
[0063] Figure 11 The figure shows the cyclic voltammetry (CV) curves of a zinc-iodine battery assembled using an asymmetric coordinated iron single-atom catalyst. The figure shows that the FeSA-N2PS catalyst exhibits the highest redox peak in its CV curve, indicating that the symmetric polarization voltage is stable when assembled with the FeSA-N2PS catalyst.
[0064] Figure 12 This image shows a bent-cut view of a zinc-iodine battery assembled using an asymmetrically coordinated iron single-atom catalyst. As can be seen from the image, the battery maintains normal function under bent-cut conditions, without short circuits or performance failure, demonstrating excellent mechanical properties and promising practical application prospects.
[0065] In summary, asymmetric coordinated iron single-atom catalysts have been successfully prepared, and zinc-iodine batteries assembled with the prepared catalysts have advantages such as high specific capacitance, good cycle stability, and safe, non-toxic, and low-cost preparation process.
[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing an asymmetric coordinated iron single-atom catalyst, characterized in that, Using polystyrene as a template, dopamine was modified and coated. FeCl3, thiourea, and hexachlorotriphosphazene were used as precursors for Fe, S, and P to prepare the PS@PDA-FeSP precursor. The asymmetric coordinated iron single-atom catalyst was obtained by high-temperature decomposition of the PS@PDA-FeSP precursor using a template-assisted method.
2. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 1, characterized in that, Includes the following steps: (1) Preparation of precursor dispersion: Polystyrene microspheres were dispersed in water and ultrasonically dispersed. Then, dopamine, FeCl3, thiourea and hexachlorotriphosphazene were added in sequence and ultrasonically dispersed again to obtain a uniform mixture. (2) In-situ polymerization reaction: The mixture obtained in step (1) is reacted under heating and stirring conditions to form a polydopamine coating layer by in-situ oxidative polymerization of dopamine, and Fe, S and P precursors are loaded simultaneously. After the reaction is completed, the mixture is separated by solid and liquid, washed and dried to obtain PS@PDA-FeSP precursor. (3) High-temperature pyrolysis: The PS@PDA-FeSP precursor obtained in step (2) is subjected to programmed temperature rise heat treatment under inert atmosphere protection, and then cooled to obtain the catalyst.
3. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (1), the mass ratio of the polystyrene microspheres, dopamine, FeCl3, thiourea and hexachlorotriphosphazene is 1:1~2:0.2~0.6:0.6~1.2:0.4~0.
8.
4. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (1), the ultrasonic dispersion time is 30-60 min; the continued ultrasonic dispersion time is 30-60 min.
5. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (2), the reaction temperature is 45~60℃ and the time is 15~18 h.
6. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (2), the solid-liquid separation method is centrifugal separation; the washing method is washing with deionized water 3 times; the drying method is vacuum drying at 50~60℃ for 10~12 h.
7. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (3), the inert atmosphere is a nitrogen atmosphere, and the gas flow rate is 40~60 mL / min.
8. The method for preparing the asymmetric coordinated iron single-atom catalyst according to claim 2, characterized in that: In step (3), the heating rate of the programmed heating heat treatment is 8 ℃ / min, the final temperature is 850 ℃, and the temperature is maintained at the final temperature for 2~3 hours.
9. An asymmetric coordinated iron single-atom catalyst, characterized in that: Prepared by the method according to any one of claims 1 to 8.
10. The application of the asymmetric coordinated iron single-atom catalyst as described in claim 9 in the preparation of the positive electrode of a zinc-iodine battery.