A macroporous prussian blue analogue single crystal and a preparation method and application thereof

Abstract

The present application relates to the technical field of electrode material, in particular to a kind of macroporous prussian blue analogue single crystal and its preparation method and application.The preparation method of the macroporous prussian blue analogue single crystal includes the following steps: the nanosphere three-dimensional template with cubic close-packed arrangement is mixed with prussian blue analogue precursor, to obtain the nanosphere three-dimensional template containing precursor;The mixed solution of chelating agent and transition metal ion is mixed with the nanosphere three-dimensional template containing precursor, and the template is removed after reaction, to obtain macroporous prussian blue analogue single crystal.The macroporous prussian blue analogue single crystal prepared by the present application is composed of interconnected macroporous prussian blue analogue nanounits in a highly ordered cubic close-packed manner, has an ordered inverse opal structure, and the macropore size can be controlled between 50-1000nm according to the size of the used template, and exhibits significant rate performance and long cycle stability when used as a positive electrode material for sodium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a macroporous Prussian blue analog single crystal, its preparation method, and its application. Background Technology

[0002] With the ever-increasing energy demand of human society and the non-renewable nature of fossil fuels, the development of renewable energy has become increasingly urgent. However, due to the intermittent nature and spatial discontinuity of renewable energy sources such as wind, solar, and tidal power, large-scale static energy storage technologies are needed to balance and suppress this intermittency, ensuring a continuous and stable output of electrical energy. Among the various secondary ion batteries currently under development, sodium-ion batteries are considered the most likely candidates for large-scale static energy storage devices because sodium is abundant on Earth, sodium-ion batteries have low production costs, and sodium-ion batteries share many physicochemical properties with lithium-ion batteries. To develop sodium-ion battery technology, scientists have been dedicated to developing cathode materials with sufficient specific capacity and ease of manufacturing.

[0003] To date, many framework materials, such as metal oxides, polyanion compounds, and oxides with tunnel structures, have been studied as cathode materials for sodium-ion batteries. However, Na... + The strong binding ability of ions in closely packed metal oxides makes their kinetics slow in intercalation reactions, while large polyanions (XO4) n– The molar weight of (X = P, S, As, Si, etc.) limits the reversible specific capacity of the material to 120 mAh g. -1 Below. Recently, Prussian blue analogues [PB, Na] have been studied. x M y [M'(CN)6] z ·nH2O, M / M'=Fe 2+ Co 2+ Ni 2+ Mn 2+ Due to its three-dimensional open framework, high two-electron redox capacity (up to 170 mAh / g), fast intercalation kinetics, high discharge plateau, low cost, and simple and environmentally friendly synthesis method, Prussian blue has received increasing attention in the field of sodium-ion batteries. Generally, Prussian blue analogues can be synthesized using transition metal ions and hexacyanoferrate Fe(CN)6. 3– / 4– Synthesis via a simple co-precipitation reaction of anions. Goodenough et al. first introduced the KMFe(CN)6 (M = Mn, Fe, Co, Ni, Cu, Zn) series of materials as cathode materials for organic sodium-ion batteries in early 2012. However, the reversible specific capacity of all these materials is less than 100 mA hg. –1The Coulomb efficiency is also limited between 60% and 80%, which is insufficient for practical battery applications. Recent studies have shown that the electrochemical performance of PB is closely related to its inherent crystal structure. During the traditional coprecipitation reaction process, due to the rapid nucleation rate, there are many [Fe(CN)6] vacancies and crystal water in the Prussian blue framework structure. The actual chemical formula of Prussian blue is Na 2-x M[Fe(CN)6] 1-y ·□ y ·zH2O, where □ represents the Fe(CN)6 vacancy; 0 < x < 2; 0 < y < 1. The presence of Fe(CN)6 vacancies and a large amount of crystal water will seriously reduce the battery performance, mainly manifested in: (1) The increase in Fe(CN)6 vacancies will lead to charge imbalance and reduce the Na content in the lattice, and introduce more water molecules into the PB framework, thus reducing the initial charge capacity; (2) The crystal water molecules may compete with Na + ions to occupy the interstitial space, thus blocking the Na + insertion reaction and reducing the capacity utilization rate of the PB compound; (3) The randomly distributed Fe(CN)6 vacancies make the PB framework fragile and prone to collapse during the Na + insertion / extraction reaction process, resulting in unstable structure and poor cycle life; (4) The crystal water in the framework structure will react with the electrolyte above 3.8V voltage, thus reducing the Coulomb efficiency of the material and the loss of manganese element. Therefore, it is very important to control the crystallization process to reduce [Fe(CN)6] vacancies and coordinated water molecules and manufacture low-defect Prussian blue analog single crystals to improve their ion storage ability.

[0004] Secondly, bulk / solid Prussian blue analogs exhibit lower mass transfer efficiency and fewer redox reaction active sites compared to their hollow or porous counterparts. Therefore, constructing hollow or porous Prussian blue analogs as cathode materials for sodium-ion batteries can significantly increase battery specific capacity and rate performance. In recent decades, two prominent structural design concepts have emerged in the development of PB (Polymer Phosphate). One is designing closed hollow structures with large cavities and thin shells, such as single-shell, multi-shell, and yolk-shell structures. Yamauchi et al. first synthesized various types of PB with yolk-shell, shell-within-shell, and yolk-double-shell hollow structures through stepwise PB crystal growth and subsequent acid etching. The other is constructing open porous structures, such as nanocages with cavities in the corners and nanoframeworks with cavities in the surfaces. Low et al. reported a self-template epitaxial growth strategy to synthesize single-crystal Prussian blue analog cages and Prussian blue analog frameworks. However, the field of hollow / porous PB is still in its early stages. In particular, the construction of interconnected and highly ordered macroporous Prussian blue analogues has not yet been achieved. However, such structures can fully expose more active sites in the material and improve mass transfer efficiency. Therefore, developing a method for constructing interconnected and highly ordered macroporous Prussian blue analogues is of great significance for improving the mass transfer efficiency of sodium-ion batteries.

[0005] Traditionally, fully interconnected and highly ordered macroporous-mesoporous materials are synthesized primarily through in-situ nucleation and growth of crystalline solutions induced within the interstices of a 3D ordered hard template. In other words, precisely controlling the nucleation rate of the crystalline solution is crucial for the synthesis of macroporous-mesoporous materials. In conventional Prussian blue (PB) preparation, due to PB's extremely low solubility product constant, nucleation and growth occur immediately and simultaneously, resulting in irregularly shaped and randomly aggregated particles. Furthermore, the strong coordination ability between metal ions (e.g., manganese ions) and ferric hexacyanoions makes precise control of PB crystallization extremely difficult; the nucleation process cannot be precisely adjusted using saturated Prussian blue precursor crystallization solutions because the bridging bonds between the cyano group and the metal ion are difficult to break. Moreover, most PB synthesis conditions are too demanding (e.g., hydrothermal, electrodeposition, and sonochemical) to be compatible with polymer templates. Therefore, developing a more general and efficient method for synthesizing macroporous-mesoporous Prussian blue is a significant challenge. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention is to provide a method for preparing macroporous Prussian blue analog single crystals, which can prepare macroporous Prussian blue single crystals with a highly ordered and fully interconnected hierarchical porous structure, wherein the macropores are adjustable and the conditions are mild.

[0007] A second aspect of the present invention is to provide a macroporous Prussian blue analog single crystal obtained by the preparation method described above.

[0008] A third aspect of the invention is to provide the application of the macroporous Prussian blue analog single crystal.

[0009] This invention is achieved through the following technical solution:

[0010] According to a first aspect of the present invention, a method for preparing a large-pore Prussian blue analog single crystal is provided, comprising the following steps:

[0011] A three-dimensional template of nanospheres with a cubic close-packed arrangement is mixed with a Prussian blue analog precursor to obtain a three-dimensional template of nanospheres containing the precursor.

[0012] The three-dimensional template containing precursor nanospheres was mixed with a mixture of chelating agent and transition metal ions. After the reaction, the template was removed to obtain a macroporous Prussian blue analog single crystal.

[0013] This invention utilizes the forming effect of a cubic close-packed nanosphere three-dimensional template and synthesizes Prussian blue analog single crystals with a fully interconnected, highly ordered macroporous structure through a chelating agent-assisted in-situ crystallization strategy. Specifically, a Prussian blue analog precursor solution is filled into the voids of a three-dimensional ordered polymer sphere template, and then transferred to a chelating agent-transition metal ion solution for in-situ crystallization. Due to the strong complexing ability of the chelating agent, the chelating agent-transition metal ion solution acts as a controller to slowly release transition metal ions within the template voids, allowing for controlled nucleation and in-situ crystallization growth of these ions in coordination with the precursor in the voids. Under the forming effect of the nanosphere template, the Prussian blue crystallization solution undergoes directional nucleation and growth, forming a macroporous Prussian blue analog single crystal with an inverse opal structure. This macroporous Prussian blue analog single crystal possesses a highly ordered and fully interconnected hierarchical porous structure, which can promote the growth of large-size Na+ crystals. + Diffusion and electrolyte permeation. Meanwhile, the entire preparation process of this invention is carried out under mild conditions.

[0014] In some embodiments of the present invention, the nanospheres include any one or more of polymer nanospheres and inorganic nanospheres, wherein the polymer nanospheres include any one or more of polystyrene nanospheres, polymethyl methacrylate nanospheres, and polylactic acid nanospheres; and the inorganic nanospheres include silica nanospheres.

[0015] In some embodiments of the present invention, the nanospheres have a particle size of 50–1000 nm, preferably 50–600 nm, more preferably 100–300 nm, such as 50 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 190 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 9000 nm, 1000 nm, etc. Preferably, the nanospheres have a uniform particle size.

[0016] In some embodiments of the present invention, the three-dimensional template of nanospheres with cubic close-packed arrangement is prepared by vacuum filtration or centrifugation of nanoscale polymer sphere emulsion or nanoscale inorganic sphere emulsion.

[0017] In some embodiments of the present invention, the three-dimensional template with cubic close-packed nanospheres is mixed with a Prussian blue analogue precursor, and then allowed to stand for 2–24 hours (preferably 10–24 hours, e.g., 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.) before being vacuum degassed and dried to obtain the three-dimensional template containing the precursor nanospheres. The vacuum degassed time is 0–2 hours, preferably 0.1–1 hour, e.g., 0.1 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, etc.

[0018] In some embodiments of the present invention, the mass ratio of the nanosphere three-dimensional template to the Prussian blue analogue precursor is 1:0.1 to 10, preferably 1:0.5 to 5, more preferably 1:0.6 to 1.3, for example 1:0.1, 1:0.5, 1:0.6, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0019] In some embodiments of the present invention, the polymer nanosphere three-dimensional template is mixed with a Prussian blue analog precursor, that is, the polymer nanosphere three-dimensional template is mixed with a Prussian blue analog precursor solution, wherein the concentration of the Prussian blue analog precursor solution is 0.05-10 mol / L, preferably 0.1-6 mol / L, and even more preferably 0.5-6 mol / L, for example 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, etc.

[0020] In some embodiments of the present invention, the Prussian blue analog precursor includes sodium ferrocyanide and potassium ferrocyanide.

[0021] In some embodiments of the present invention, the molar ratio of the Prussian blue analog precursor to the transition metal ion is 1:0.1 to 1, preferably 1:0.1 to 0.8, more preferably 1:0.2 to 0.6, for example 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0022] In some embodiments of the present invention, the molar ratio of the chelating agent to the transition metal ion is 0.2 to 15:1, preferably 0.4 to 10:1, more preferably 1 to 5:1, for example 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0023] In some embodiments of the present invention, the concentration of the chelating agent in the mixture of the chelating agent and transition metal ions is 0.05–10 mol / L, preferably 0.05–16 mol / L, more preferably 0.05–2 mol / L, even more preferably 0.1–1.5 mol / L, and more preferably 0.5–1.5 mol / L. Examples include 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, etc.

[0024] In some embodiments of the present invention, after the three-dimensional template containing precursor nanospheres is mixed with a chelating agent and transition metal ions, it is subjected to vacuum treatment for 0–2 hours (preferably 10 min–1 hour, e.g., 10 min, 15 min, 20 min, 30 min, 40 min, 1 hour, 1.5 hour, 2 hours, etc.) and then allowed to stand for 0–24 hours (preferably 5–20 hours, e.g., 1, 3, 5, 7, 9, 10, 15, 20, 24 hours, etc.). After standing, steps such as filtration, washing, and drying can be performed.

[0025] In some embodiments of the present invention, the chelating agent includes any one or more of sodium citrate, sodium oxalate, and sodium hypophosphite.

[0026] In some embodiments of the present invention, the transition metal ion includes any one or more of cobalt ions, manganese ions, ferrous ions, and nickel ions. Depending on the type of transition metal ion, different macroporous Prussian blue analog single crystals are obtained. For example, when the transition metal is cobalt ions, macroporous Prussian green single crystals are obtained; when the transition metal ion is manganese ions, macroporous Prussian white single crystals are obtained; and when the transition metal is ferrous ions, macroporous Prussian blue single crystals are obtained.

[0027] In some embodiments of the present invention, the method for removing the template is as follows: for polymer nanosphere three-dimensional templates, the product is immersed in a polar organic solvent, followed by solid-liquid separation to obtain the macroporous Prussian blue analog single crystal; for inorganic nanosphere three-dimensional templates, immersion in acid or alkali is performed, for example, for silica nanosphere three-dimensional templates, immersion in hydrofluoric acid or sodium hydroxide solution. The immersion and solid-liquid separation steps can be repeated multiple times, for example, 2 to 5 times, preferably 2, 3, or 4 times. Preferably, the immersion time is 12 to 72 hours, more preferably 12 to 24 hours.

[0028] In some embodiments of the present invention, the polar organic solvent includes any one or more of tetrahydrofuran, dichloromethane, N,N-dimethylformamide, toluene, xylene, and chloroform.

[0029] Apart from the necessary drying steps and the preparation steps related to the three-dimensional template of nanospheres, the preparation method of macroporous Prussian blue analog single crystals of the present invention is carried out at a temperature of 0–50°C, preferably 10–30°C, and more preferably 20–25°C. In actual operation, it is not necessary to specifically limit the reaction temperature during the preparation process.

[0030] The drying step of this invention uses a drying temperature commonly used in the art, such as 50 to 100°C, preferably 60 to 80°C.

[0031] In the solution system of this invention, the solvent used includes any one or a mixture of water, ethanol, methanol, and isopropanol. Preferably, the solvent in the nanoscale polymer sphere emulsion includes any one or a mixture of water, methanol, ethanol, isopropanol, and acetone. Preferably, the solvent in the Prussian blue analogue precursor solution includes any one or a mixture of water, ethanol, methanol, and isopropanol.

[0032] According to a second aspect of the present invention, a macroporous Prussian blue analog single crystal obtained by the above-described preparation method is provided. The macroporous Prussian blue analog single crystal is composed of interconnected nanounits arranged in an ordered cubic close-packed manner, possessing an ordered inverse opal structure. Its macropore size can be controlled between 50 and 1000 nm depending on the size of the template used. Generally, the macropore size of the macroporous Prussian blue analog single crystal is the same as or similar to the size of the three-dimensional nanosphere template. The size of the macroporous Prussian blue analog single crystal is 0.1–5 μm, preferably 0.1–1 μm, and even more preferably 0.2–0.8 μm.

[0033] According to a third aspect of the invention, an electrode is provided, wherein the macroporous Prussian blue analog single crystal is attached to the electrode.

[0034] In some embodiments of the present invention, the electrode includes a substrate coated with the macroporous Prussian blue analogue single crystal. The substrate may be a common electrode substrate, such as copper, glassy carbon, titanium, stainless steel, and various metal alloys.

[0035] The present invention also provides a sodium-ion battery, wherein the sodium-ion battery includes the electrode, or the sodium-ion battery contains the macroporous Prussian blue analog single crystal. The electrode can serve as the positive electrode of the sodium-ion battery, that is, the macroporous Prussian blue analog single crystal can serve as the positive electrode material of the sodium-ion battery.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The single crystal prepared by this invention is the first ordered macroporous single crystal cobalt-based Prussian blue analog in the field of cobalt-based Prussian blue analogs. Its macropore diameter can be controlled between 50 and 1000 nm according to the diameter of the template used. Currently, hollow or porous cobalt-based Prussian blue analogs reported in literature and patents are all core-shell, eggshell, multi-shell structures or nanocages with hollow corners or open nanoframeworks. There has been no report of cobalt-based Prussian blue analog single crystals with highly ordered macropores.

[0038] (2) The preparation process of this invention is simple, green and environmentally friendly, and low in cost. Most importantly, the ordered macroporous Prussian blue analog single crystal obtained has a large redox active surface. When used as the positive electrode material of sodium-ion battery, it exhibits significant rate performance and long cycle stability. Attached Figure Description

[0039] Figure 1 A scanning electron microscope (SEM) image of a macroporous cobalt-based Prussian green single crystal from Example 1;

[0040] Figure 2Transmission electron microscope (TEM) image of a single macroporous cobalt-based Prussian green single crystal of Example 1;

[0041] Figure 3 X-ray diffraction (XRD) image of macroporous cobalt-based Prussian green single crystal of Example 1;

[0042] Figure 4 A scanning electron microscope (SEM) image of a macroporous manganese-based Prussian white single crystal from Example 15;

[0043] Figure 5 X-ray diffraction (XRD) image of macroporous manganese-based Prussian white single crystal of Example 15;

[0044] Figure 6 Transmission electron microscope (TEM) image of a single macroporous manganese-based Prussian white single crystal of Example 15;

[0045] Figure 7 A scanning electron microscope (SEM) image of a macroporous iron-based Prussian blue single crystal from Example 29;

[0046] Figure 8 X-ray diffraction (XRD) image of a macroporous iron-based Prussian blue single crystal of Example 29;

[0047] Figure 9 Transmission electron microscope (TEM) image of a single macroporous iron-based Prussian blue single crystal of Example 29;

[0048] Figure 10 A scanning transmission electron microscope (STEM) image of a single macroporous iron-based Prussian blue single crystal of Example 29;

[0049] Figure 11 Low-current cycling diagram, rate performance diagram, and high-current cycling diagram of a single macroporous iron-based Prussian blue single crystal of Example 29 as a cathode material for sodium-ion batteries.

[0050] Figure 11 Low-current cycling diagram, rate performance diagram, and high-current cycling diagram of a single macroporous iron-based Prussian blue single crystal of Example 29 as a cathode material for sodium-ion batteries.

[0051] Figure 12 This is a scanning electron microscope (SEM) image of a macroporous iron-based Prussian blue single crystal from Example 30. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below with reference to specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from conventional commercial channels; unless otherwise specified, the processes employed are conventional processes in the art.

[0053] The polymer nanosphere three-dimensional template used in this invention can be prepared by the following method: mixing monomer, water, and surfactant to obtain a monomer dispersion; adding an initiator to the monomer dispersion to initiate the polymerization reaction of the monomer to obtain a nanoscale polymer sphere emulsion; and vacuum filtering or centrifuging the nanoscale polymer sphere emulsion to obtain polymer nanospheres.

[0054] In the monomer dispersion, the monomer concentration is 0.01–1 mL / mL, preferably 0.1–0.2 mL / mL, for example 0.01 mL / mL, 0.02 mL / mL, 0.05 mL / mL, 0.08 mL / mL, 0.1 mL / mL, 0.12 mL / mL, 0.14 mL / mL, 0.16 mL / mL, 0.18 mL / mL, 0.2 mL / mL, 0.25 mL / mL, 0.3 mL / mL, 0.35 mL / mL, 0.4 mL / mL, 0.45 mL / mL, 0.5 mL / mL, 0.55 mL / mL, 0.6 mL / mL, 0.65 mL / mL, 0.7 mL / mL, 0.75 mL / mL, 0.8 mL / mL, 0.85 mL / mL, 0.9 mL / mL, 0.95 mL / mL, 1 mL / mL, etc.

[0055] Before use, the stabilizer used to preserve the monomer needs to be removed. The monomer is a polymer monomer well-known in the art; for example, for polystyrene nanospheres, the monomer is styrene; for polymethyl methacrylate nanospheres, the monomer is methyl methacrylate; and for polylactic acid nanospheres, the monomer is lactic acid.

[0056] In the monomer dispersion, the concentration of the surfactant is 1-20 g / 100 mL, preferably 1-10 g / 100 mL, such as 1 g / 100 mL, 2 g / 100 mL, 4 g / 100 mL, 5 g / 100 mL, 6 g / 100 mL, 8 g / 100 mL, 10 g / 100 mL, 12 g / 100 mL, 14 g / 100 mL, 15 g / 100 mL, 16 g / 100 mL, 18 g / 100 mL, 20 g / 100 mL, etc.

[0057] Surfactants include any one or more of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol, and sodium dodecyl sulfate.

[0058] The ratio of monomer to initiator is 10-100 mL / g, preferably 20-80 mL / g, more preferably 50-80 mL / g, for example 10 mL / g, 15 mL / g, 20 mL / g, 25 mL / g, 30 mL / g, 35 mL / g, 40 mL / g, 45 mL / g, 50 mL / g, 55 mL / g, 60 mL / g, 65 mL / g, 70 mL / g, 75 mL / g, 80 mL / g, 85 mL / g, 90 mL / g, 95 mL / g, 100 mL / g, etc.

[0059] The initiator includes any one or more of potassium persulfate, ammonium persulfate, sodium persulfate, azobisisobutyronitrile, and azobisisoheptanenitrile.

[0060] The polymerization temperature is 50–150℃, preferably 65–120℃, and even more preferably 90–110℃, for example 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 94℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc. Generally, polymer nanospheres with larger particle sizes can be obtained at lower polymerization temperatures, and the particle size of polymer nanospheres tends to decrease as the polymerization temperature increases.

[0061] The polymerization time can be adjusted appropriately according to the reaction temperature and the scale of the reaction. For example, the reaction time can be shortened when using a higher reaction temperature, and extended when the reaction scale is larger. As an example, when the monomer dosage is 60–80 mL and the concentration is 0.1–0.2 mL / mL, the polymerization reaction time at 90–110 °C is 10–60 min, preferably 20–40 min. Under other conditions, the polymerization reaction time can be appropriately shortened or extended.

[0062] The polymerization reaction is carried out in a protective atmosphere, such as nitrogen or argon.

[0063] Several specific 3D templates are provided below, which can be used to prepare large-pore Prussian blue analog single crystals.

[0064] (1) 3D Template 1

[0065] 500 mL of deionized water, 65 mL of stabilizer-free styrene, and 2.5 g of polyvinylpyrrolidone (PVP K55) were sequentially added to a 1 L three-necked flask. The mixture was magnetically stirred at room temperature and purged with nitrogen for 15 min. Subsequently, the system was heated to 94 °C under nitrogen protection and held for 30 min. Then, 50 mL of an aqueous solution containing 1 g of K₂S₂O₈ was immediately poured into a round-bottom flask to initiate the polymerization reaction of styrene. After 24 hours, the reaction was completed. The resulting milky white reaction emulsion was filtered, washed, and the collected filter cake was dried in an 80 °C vacuum oven for 24 h. The dried white filter cake served as a three-dimensional template for the stacking of polystyrene nanospheres, with the polystyrene microspheres measuring approximately 190 nm in size.

[0066] (2) 3D Template 2

[0067] 500 mL of deionized water, 65 mL of stabilizer-free styrene, and 2.5 g of polyvinylpyrrolidone (PVP) were sequentially added to a 1 L three-necked flask. The mixture was magnetically stirred at room temperature and purged with nitrogen for 15 min. Subsequently, the system was heated to 105 °C under argon protection and held for 30 min. Then, 50 mL of an aqueous solution containing 1.1 g of K₂S₂O₈ was immediately poured into a round-bottom flask to initiate the polymerization reaction of styrene. After 24 hours, the reaction was completed. The resulting milky white reaction emulsion was filtered, washed, and the collected filter cake was dried in an 80 °C vacuum oven for 24 h. The dried white filter cake served as a three-dimensional template for the stacking of polystyrene nanospheres, with the polystyrene microspheres measuring approximately 160 nm in size.

[0068] (3) 3D Template 3

[0069] 500 mL of deionized water, 65 mL of stabilizer-free styrene, and 2.5 g of polyvinylpyrrolidone (PVP) were sequentially added to a 1 L three-necked flask. The mixture was magnetically stirred at room temperature and purged with nitrogen for 15 min. Subsequently, the system was heated to 105 °C under argon protection and held for 30 min. Then, 50 mL of an aqueous solution containing 1.2 g of K₂S₂O₈ was immediately poured into a round-bottom flask to initiate the polymerization reaction of styrene. After 24 hours, the reaction was completed. The resulting milky white reaction emulsion was filtered, washed, and the collected filter cake was dried in an 80 °C vacuum oven for 24 h. The dried white filter cake served as a three-dimensional template for the stacking of polystyrene nanospheres, with the polystyrene microspheres measuring approximately 100 nm in size.

[0070] (4) 3D Template 4

[0071] 500 mL of deionized water, 65 mL of stabilizer-free styrene, and 2.5 g of polyvinylpyrrolidone (PVP) were sequentially added to a 1 L three-necked flask. The mixture was magnetically stirred at room temperature and purged with nitrogen for 15 min. Subsequently, the system was heated to 65 °C under argon protection and held for 30 min. Immediately afterward, 50 mL of an aqueous solution containing 1.0 g of K₂S₂O₈ was poured into a round-bottom flask to initiate the polymerization reaction of styrene. After 24 hours, the reaction was completed. The resulting milky white reaction emulsion was filtered, washed, and the collected filter cake was dried in an 80 °C vacuum oven for 24 h. The dried white filter cake served as a three-dimensional template for the stacking of polystyrene nanospheres, with the polystyrene microspheres measuring approximately 340 nm in size.

[0072] (5) 3D Template 5

[0073] 500 mL of deionized water, 65 mL of stabilizer-free styrene, and 2.5 g of polyvinylpyrrolidone (PVP) were sequentially added to a 1 L three-necked flask. The mixture was magnetically stirred at room temperature and purged with nitrogen for 15 min. Subsequently, the system was heated to 75 °C under argon protection and held for 30 min. Then, 50 mL of an aqueous solution containing 1.1 g of K₂S₂O₈ was immediately poured into a round-bottom flask to initiate the polymerization reaction of styrene. After 24 hours, the reaction was completed. The resulting milky white reaction emulsion was filtered, washed, and the collected filter cake was dried in an 80 °C vacuum oven for 24 h. The dried white filter cake served as a three-dimensional template for the stacking of polystyrene nanospheres, with the polystyrene microspheres measuring approximately 270 nm in size.

[0074] Various macroporous Prussian blue analogue single crystals were prepared using the aforementioned three-dimensional template. In the following examples, unless otherwise specified, all reactions were carried out at room temperature (20–25°C).

[0075] Example 1

[0076] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0077] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals (labeled as OMMS-CoFe-HCF).

[0078] Figure 1 Scanning electron microscope (SEM) images of macroporous cobalt-based Prussian green single crystals prepared in this embodiment show that the crystals are composed of interconnected macroporous Prussian blue analog nanounits in a highly ordered cubic close-packed manner, with an ordered inverse opal structure. The crystal size is approximately 0.6 μm, and its surface has a large number of ordered macroporous structures with an ordered macroporous size of approximately 190 nm. Figure 2 The image is a transmission electron microscope (TEM) image of a single macroporous cobalt-based Prussian green single crystal. It can be clearly seen that the macropores are distributed throughout the entire crystal and are highly ordered. Figure 3 The image shows an X-ray diffraction (XDR) image of a macroporous cobalt-based Prussian green single crystal. The high intensity of the diffraction peaks is clearly visible, and the peaks correspond perfectly to the standard card, proving the single-crystal properties of the synthesized macroporous Prussian green.

[0079] Example 2

[0080] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0081] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (8g) of sodium citrate and 0.834g of cobalt acetate (100mL), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals with ordered macropore size of 190nm.

[0082] Example 3

[0083] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0084] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (10g) of sodium citrate and cobalt acetate (0.834g) (100mL), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals with ordered macropore size of 190nm.

[0085] Example 4

[0086] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0087] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (12g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals with ordered macropore size of 190nm.

[0088] Example 5

[0089] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0090] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (2g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals with ordered macropore size of 190nm.

[0091] Example 6

[0092] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0093] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (4g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous cobalt-based Prussian green single crystal with an ordered macropore size of 190nm.

[0094] Example 7

[0095] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0096] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (5g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous cobalt-based Prussian green single crystals with ordered macropore size of 190nm.

[0097] Example 8

[0098] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0099] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 24h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (5g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 190nm.

[0100] Example 9

[0101] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0102] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2 hours, degas under vacuum for 1 hour. Then, remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (5g) and cobalt acetate (0.834g). After vacuum treatment for 15 minutes, let it stand for 24 hours, then filter, wash, and dry it. Soak the dried polymer template in DMF for 24 hours, centrifuge to collect the precipitate, and repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 190nm.

[0103] Example 10

[0104] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0105] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium oxalate (5g) and cobalt acetate (0.834g), vacuum treat for 15min, and let it stand for 6h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 190nm.

[0106] Example 11

[0107] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0108] Weigh 4g of the three-dimensional template 2 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2 hours, degas under vacuum for 1 hour. Then, remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and cobalt acetate (0.834g). After vacuum treatment for 15 minutes, let it stand for 24 hours, then filter, wash, and dry it. Soak the dried polymer template in DMF for 24 hours, centrifuge to collect the precipitate, and repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 160nm.

[0109] Example 12

[0110] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0111] 4g of the three-dimensional template 3 was weighed and added to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2 hours, the template was degassed under vacuum for 1 hour. The template was then removed and dried to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. The obtained three-dimensional template containing sodium ferrocyanide nanospheres was added to a mixed solution (100mL) of sodium citrate (5g) and cobalt acetate (0.834g). After vacuum treatment for 15 minutes, the template was allowed to stand for 24 hours, then filtered, washed, and dried. The dried polymer template was then immersed in DMF for 24 hours, centrifuged to collect the precipitate, and then immersed in DMF again. This process was repeated three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 340nm.

[0112] Example 13

[0113] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0114] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (3.63g) solution (50mL). After standing for 2 hours, degas under vacuum for 1 hour. Then, remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and cobalt acetate (0.834g). After vacuum treatment for 15 minutes, let it stand for 24 hours, then filter, wash, and dry it. Soak the dried polymer template in DMF for 24 hours, centrifuge to collect the precipitate, and repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 190nm.

[0115] Example 14

[0116] This embodiment prepares a macroporous cobalt-based Prussian green single crystal, and the preparation method includes the following steps:

[0117] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (4.84g) solution (50mL). After standing for 2 hours, degas under vacuum for 1 hour. Then, remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and cobalt acetate (0.834g). After vacuum treatment for 15 minutes, let it stand for 24 hours, then filter, wash, and dry it. Soak the dried polymer template in DMF for 24 hours, centrifuge to collect the precipitate, and repeat this process three times to obtain a single crystal of Prussian blue analogue with an ordered macropore size of 190nm.

[0118] Example 15

[0119] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0120] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (10g) of sodium citrate and manganese chloride (0.834g) (100mL), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals (labeled as OMMS-MnFe-HCF).

[0121] Figure 4 The scanning electron microscope (SEM) image of the macroporous manganese-based Prussian white single crystal prepared in this embodiment shows that the crystal size is about 2.5 μm and its surface has a large number of ordered macroporous structures with an ordered macroporous size of about 190 nm. Figure 5 The XRD pattern of the macroporous manganese-based Prussian white single crystal shows that the diffraction peaks correspond perfectly with the standard card, indicating the high crystallinity of the synthesized Prussian white single crystal. Figure 6 The image is a transmission electron microscope (TEM) image of a single macroporous manganese-based Prussian white single crystal. It can be clearly seen that the macropores are distributed throughout the entire crystal and are highly ordered.

[0122] Example 16

[0123] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0124] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (8g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0125] Example 17

[0126] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0127] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 270nm.

[0128] Example 18

[0129] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0130] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 2h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (12g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0131] Example 19

[0132] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0133] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (15g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0134] Example 20

[0135] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0136] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (17.5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Rosé white single crystals with an ordered macropore size of 190nm.

[0137] Example 21

[0138] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0139] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in N,N-dimethylformamide solvent DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0140] Example 22

[0141] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0142] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 24h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0143] Example 23

[0144] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0145] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0146] Example 24

[0147] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0148] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 6h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0149] Example 25

[0150] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0151] Weigh 4g of the three-dimensional template 2 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 160nm.

[0152] Example 26

[0153] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0154] Weigh 4g of the three-dimensional template 4 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 340nm.

[0155] Example 27

[0156] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0157] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (3.63g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0158] Example 28

[0159] This embodiment prepares a macroporous manganese-based Prussian white single crystal, and the preparation method includes the following steps:

[0160] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (4.84g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and manganese chloride (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain macroporous manganese-based Prussian white single crystals with ordered macropore size of 190nm.

[0161] Example 29

[0162] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0163] Weigh 4g of the three-dimensional template 5 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and repeat this process three times to obtain macroporous iron-based Prussian blue single crystals (labeled as OMMS-Fe-HCF).

[0164] Figure 7 Scanning electron microscope (SEM) images of the macroporous iron-based Prussian blue single crystal prepared for this embodiment show that the crystal size is approximately 2 μm, and its surface has a large number of ordered macroporous structures. The size of the ordered macropores is 270 nm. Figure 8 The XRD pattern of the macroporous iron-based Prussian blue single crystal shows that the prepared single crystal has no other impurity peaks, indicating a high degree of crystallinity. Figure 9 The transmission electron microscope (TEM) image of a single macroporous iron-based Prussian blue single crystal clearly shows that the macropores in the sample are distributed throughout the entire crystal and are highly ordered. Figure 10 The image is a scanning transmission electron microscope (STEM) image of a macroporous iron-based Prussian blue single crystal, which allows for a clearer view of the crystal's internal macroporous structure.

[0165] Electrodes were fabricated using this macroporous iron-based Prussian blue single crystal. The preparation method involved uniformly mixing the macroporous iron-based Prussian blue single crystal, Ketjen Black, and PVDF at a mass ratio of 8:1:1. 31 drops of N-methylpyrrolidone (NMP) were then added dropwise to form a homogeneous slurry. This slurry was then uniformly coated onto a copper foil using a 75-micron thick coating tool and dried in a vacuum dryer at 80°C for 12 hours. The active material loading mass was 0.8–1.0 mg / cm³. –2 A 1.0 M sodium hexafluorophosphate (NaPF6) / DIGLYME electrolyte was used; a 16 mm diameter Whatman glass microfiber (GF / F) was used as the separator; this was used as the positive electrode, and a sodium metal sheet was used as the counter and reference electrode. Electrochemical performance was measured by assembling 2032 coin cells in an Ar-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm). Constant current charge-discharge performance and rate capability were tested using a NEWARE battery testing system within a voltage window of 0.001–3.0 V.

[0166] Figure 11 The figures show the short-cycle performance, rate performance, and long-cycle performance of this macroporous iron-based Prussian blue single crystal as a cathode in sodium-ion batteries. As can be seen from the figures, the macroporous iron-based Prussian blue single crystal exhibits excellent cycle performance as a cathode in sodium-ion batteries: at 25 mA g... –1 At high current density, the initial discharge specific capacity is 93.8 mA hg. –1 The initial coulombic efficiency was 98.9%. After 100 cycles, the charge-discharge capacity remained stable with a capacity retention of 86% and a coulombic efficiency of 97.8%. At 0.5 mA g... –1 At the current density, the initial discharge specific capacity is 93.9 mA hg. –1The initial coulombic efficiency was 91.6%. After 1000 cycles, the charge-discharge capacity remained stable with a capacity retention of 60%, and the coulombic efficiency was 94.5%. Furthermore, the rate performance test results show that at 0.025, 0.05, 0.1, 0.2, 0.5, and 1.0 A g... –1 At the specified current densities, the discharge capacities of macroporous single crystals were 88.3, ​​82.6, 77.2, 69.1, 58.0, and 41.2 mA hg, respectively. –1 When the current density recovers to 0.025 A g –1 The discharge specific capacity recovered to 83.6 mA hg –1 The large-pore iron-based Prussian blue single crystal exhibits excellent rate performance when used as the positive electrode in sodium-ion batteries.

[0167] Example 30

[0168] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0169] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (8g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and repeat this process three times to obtain macroporous iron-based Prussian blue single crystals.

[0170] Figure 12 The scanning electron microscope (SEM) image of the macroporous iron-based Prussian blue single crystal prepared in this embodiment shows that the crystal size is mainly distributed in the range of 1.5 to 2.0 μm, and there are a large number of ordered macroporous structures on its surface, with an ordered macroporous size of 190 nm.

[0171] Example 31

[0172] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0173] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (10g) of sodium citrate and ferrous sulfate (0.834g) (100mL), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0174] Example 32

[0175] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0176] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (12g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0177] Example 33

[0178] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0179] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (15g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0180] Example 34

[0181] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0182] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (17.5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0183] Example 35

[0184] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0185] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0186] Example 36

[0187] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0188] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 24h, degas under vacuum for 0.5h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 12h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0189] Example 37

[0190] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0191] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0192] Example 38

[0193] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0194] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 6h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0195] Example 39

[0196] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0197] Weigh 4g of the three-dimensional template 5 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 160nm.

[0198] Example 40

[0199] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0200] Weigh 4g of the three-dimensional template 4 and add it to a sodium ferrocyanide (2.42g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 340nm.

[0201] Example 41

[0202] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0203] Weigh 4g of the three-dimensional template 1 and add it to a sodium ferrocyanide (3.63g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide nanospheres. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0204] Example 42

[0205] This embodiment prepares a macroporous iron-based Prussian blue single crystal, and the preparation method includes the following steps:

[0206] Weigh 4g of three-dimensional template 1 and add it to a sodium ferrocyanide (5.24g) solution (50mL). After standing for 12h, degas under vacuum for 1h, and then remove the three-dimensional template and dry it to obtain a three-dimensional template containing sodium ferrocyanide. Add the obtained three-dimensional template containing sodium ferrocyanide nanospheres to a mixed solution (100mL) of sodium citrate (5g) and ferrous sulfate (0.834g), vacuum treat for 15min, and let it stand for 24h. Then filter, wash, and dry it. Soak the dried polymer template in DMF for 24h, centrifuge to collect the precipitate, and soak it in DMF again. Repeat this process three times to obtain a macroporous iron-based Prussian blue single crystal with an ordered macropore size of 190nm.

[0207] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a single crystal of a macroporous Prussian blue analogue, characterized in that: Includes the following steps: A three-dimensional template of nanospheres with a cubic close-packed arrangement is mixed with a Prussian blue analog precursor to obtain a three-dimensional template of nanospheres containing the precursor. The three-dimensional template containing precursor nanospheres was mixed with a mixture of chelating agent and transition metal ions. After the reaction, the template was removed to obtain a macroporous Prussian blue analog single crystal. The chelating agent includes any one or more of sodium citrate, sodium oxalate, and sodium hypophosphite; the molar ratio of the chelating agent to the transition metal ion is 0.2~15:1; the mass ratio of the nanosphere three-dimensional template to the Prussian blue analog precursor is 1:0.1~10; and the molar ratio of the Prussian blue analog precursor to the transition metal ion is 1:0.1~1.

2. The preparation method according to claim 1, characterized in that: The nanospheres have a particle size of 50~1000 nm.

3. The preparation method according to claim 1, characterized in that: The transition metal ions include any one or more of cobalt ions, manganese ions, ferrous ions, and nickel ions.

4. The macroporous Prussian blue analog single crystal obtained by the preparation method according to any one of claims 1 to 3, wherein the macroporous Prussian blue analog single crystal is composed of interconnected nanounits in an ordered cubic close-packed manner, and has an ordered inverse opal structure.

5. An electrode, characterized in that: The electrode is attached with a macroporous Prussian blue analogue single crystal as described in claim 4.

6. A sodium-ion battery, characterized in that: The sodium-ion battery includes the electrode of claim 5, or the sodium-ion battery contains a macroporous Prussian blue analog single crystal of claim 4.

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