A method for preparing iron oxide nanoparticles with controllable morphology and particle size

Abstract

This invention discloses a method for preparing Fe3O4 nanoparticles with controllable morphology and particle size. The method includes: S1, dissolving iron salt in a polyol, sonicating and stirring until the iron salt no longer dissolves; S2, adding a structure-directing agent, continuing stirring, transferring the resulting liquid to a reaction vessel, sealing, and reacting at high temperature; S3, after the reaction is complete, naturally cooling to room temperature, and washing the resulting black product several times with deionized water and ethanol to obtain Fe3O4 nanoparticles. The method of this invention is simple to operate, has a high yield, and the morphology and particle size of the prepared Fe3O4 microspheres can be controlled.

Description

Technical Field

[0001] This invention relates to the field of methods for preparing iron oxide nanoparticles, and more particularly to a method for preparing iron oxide nanoparticles with controllable morphology and particle size. Background Technology

[0002] Fe3O4 magnetic nanoparticles are characterized by simple preparation, high stability, low cost, good biocompatibility, good magnetic responsiveness, and easy surface modification. They are widely used in biochemical fields such as nucleic acid extraction, cell sorting, protein purification, nuclear magnetic resonance imaging, drug targeting, and magnetothermal therapy.

[0003] Currently, magnetic Fe3O4 nanoparticles can be prepared by methods such as chemical coprecipitation, hydrothermal methods, thermal decomposition, and solvothermal methods. Among these, the coprecipitation method involves a low reaction temperature, resulting in poor monodispersity of the nanoparticles. Furthermore, the nanoparticles are prone to aggregation or oxidation during washing, making it unsuitable for producing monodisperse Fe3O4 nanoparticles. The hydrothermal method, based on harsh experimental conditions such as high temperature and pressure, prepares monodisperse nanoparticles through metal ion crystallization, but subsequent processing still leads to oxidation of the nanoparticles in the air, affecting their chemical composition. Thermal decomposition produces high-purity, non-agglomerated Fe3O4 nanoparticles, but requires stringent conditions and is costly. The solvothermal method is one of the most commonly used methods for preparing magnetic Fe3O4 nanoparticles. The reaction is carried out in a closed, high-pressure hydrothermal reactor, producing Fe3O4 nanoparticles with uniform morphology, good dispersibility, and controllable size, attracting widespread attention from researchers. However, this method requires a high-pressure, closed container, resulting in extremely low preparation efficiency and hindering large-scale industrial production. For example, CN113636601A discloses a solvent-based method for preparing magnetic iron oxide nanoparticles, in which the mass ratio of ferric chloride hexahydrate, ethylene glycol, sodium citrate, and anhydrous sodium acetate is 15:555:36:24, and the proportion of ferric chloride is only 2.7%; CN116332240A discloses a solvent-based method for preparing magnetic iron oxide nanoparticles, in which the proportion of ferric chloride in the solvent is at most 12.7%; CN110615483A discloses a solvent-based method for preparing magnetic Fe3O4 microspheres, in which the proportion of ferric chloride in the solvent is at most 10%; CN117566807A discloses a solvent-based method for preparing magnetic iron oxide nanoparticles, in which the concentration of ferric ion compound is 0.005–0.5 mol / L. Furthermore, the particles prepared by this method are relatively large, making it difficult to prepare iron oxide nanoparticles with uniform sizes below 100 nm.

[0004] Therefore, there is an urgent need to develop a method for preparing iron oxide nanoparticles that can be mass-produced and whose morphology and particle size can be controlled. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing iron oxide nanoparticles that can be mass-produced and whose morphology and particle size can be controlled.

[0006] To achieve the above objectives, this invention provides a method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size, characterized by comprising the following steps:

[0007] S1. Dissolve the iron salt in the polyol, and sonicate and stir until the iron salt no longer dissolves.

[0008] S2. Add the structure guiding agent, continue stirring, transfer the resulting liquid to the reactor, seal, and react at high temperature;

[0009] S3. After the reaction is complete, the product is naturally cooled to room temperature. The resulting black product is washed several times with deionized water and ethanol to obtain iron oxide nanoparticles.

[0010] Furthermore, in S1, the iron salt is at least one of ferric acetylacetone, potassium ferrocyanide, ferrocene, ferric sulfate, ferric nitrate, and ferric chloride.

[0011] Furthermore, in S1, the polyol used as a solvent is at least one of ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and glycerol.

[0012] Furthermore, in S1, the concentration of the iron salt after dissolving in the polyol is 50 w / v% to 100 w / v.

[0013] Furthermore, in S2, the structure guiding agent is at least one of sodium citrate, anhydrous sodium acetate, urea, polyethyleneimine, potassium nitrate, polyethylene glycol, potassium permanganate, sodium hydroxide, ethylenediamine, and polyvinylpyrrolidone.

[0014] Optionally, the amount of the structure guiding agent added is 6 w / v% to 180 w / v.

[0015] Furthermore, in step S3, the high-temperature reaction is carried out at 180–220°C for 8–24 hours.

[0016] Furthermore, the morphology of the iron oxide nanoparticles obtained in S3 is spherical, rod-shaped, polyhedral, hollow sphere, pine cone-shaped, or honeycomb-shaped, with a size of 30–400 nm.

[0017] Different morphologies of iron oxide nanoparticles exhibit different magnetic responsiveness, meaning they have different magnetic separation times. Furthermore, magnetic beads with different morphologies, after being encapsulated with silica, have different numbers of silanol groups, resulting in varying nucleic acid extraction rates.

[0018] This invention utilizes different structure-guiding agents to induce variations in the shape of the prepared iron(III) oxide nanoparticles. For example, with the addition of urea, under high vapor pressure, urea and H2O generate CO2 and NH3, and these microbubbles remain in the reaction medium. With the assistance of the reaction medium, crystals form, and these microbubbles act as aggregation centers, guiding the crystals to aggregate around the gas-liquid interface. As crystal growth and Ostwarld ripening proceed, hollow spherical magnetic beads are eventually formed. Increasing the urea content in the system leads to an increase in precipitated ions and generated microbubbles. Under these conditions, violent collisions occur within the container, destroying the hollow core. The hydrolysis of urea produces a large number of negatively charged anions (OH-). - and CO3 2- The grains formed by the encapsulation aggregate under the drive of surface tension. As the Ostwald ripening process proceeds, the positively charged NH4+... 4+ They are highly likely to adsorb onto the surface of the grains, thus hindering particle growth and forming pinecone-shaped magnetic beads. The mechanisms by which magnetic beads are formed differ depending on the guiding principle.

[0019] Compared with the prior art, this application has the following beneficial effects:

[0020] This invention uses Fe 3+ Using iron as a source, after dissolving it in a solvent, a specific structure-directing agent is added, and Fe is partially reduced via a solvothermal method. 3+ This invention provides a one-step synthesis of Fe3O4 microspheres with adjustable grain size and magnetic response (i.e., magnetic separation time). The method of this invention is simple to operate, has a high yield, and the morphology and particle size of the prepared Fe3O4 microspheres can be controlled. Attached Figure Description

[0021] Figure 1 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 1.

[0022] Figure 2 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 2.

[0023] Figure 3 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 3.

[0024] Figure 4 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 4.

[0025] Figure 5 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 5.

[0026] Figure 6 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 6.

[0027] Figure 7 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 7.

[0028] Figure 8 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 8.

[0029] Figure 9 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 9.

[0030] Figure 10 This is a morphological structure diagram of the Fe3O4 magnetic particles obtained in Example 10.

[0031] Figure 11 This is a diagram showing the morphological structure of the magnetic beads obtained in Comparative Example 1.

[0032] Figure 12 This is a diagram showing the morphological structure of the magnetic beads obtained in Comparative Example 2. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0034] The magnetic separation time of the magnetic beads in the following experiment: Accurately weigh 0.1g of sample powder, add 10mL of water to a 10mL glass bottle, disperse it fully by ultrasound, place a magnet vertically on one side of the glass bottle, and calculate the time it takes for the solution to go from turbid to clear.

[0035] A method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size, characterized by comprising the following steps:

[0036] S1. Dissolve the iron salt in the polyol, and sonicate and stir until the iron salt no longer dissolves.

[0037] S2. Add the structure guiding agent, continue stirring, transfer the resulting liquid to the reactor, seal, and react at high temperature;

[0038] S3. After the reaction is complete, the product is naturally cooled to room temperature. The resulting black product is washed several times with deionized water and ethanol to obtain iron oxide nanoparticles.

[0039] Furthermore, in S1, the iron salt is at least one of ferric acetylacetone, potassium ferrocyanide, ferrocene, ferric sulfate, ferric nitrate, and ferric chloride.

[0040] Furthermore, in S1, the polyol used as a solvent is at least one of ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and glycerol.

[0041] Furthermore, in S1, the concentration of the iron salt after dissolving in the polyol is 50 w / v% to 100 w / v.

[0042] Furthermore, in S2, the structure guiding agent is at least one of sodium citrate, anhydrous sodium acetate, urea, polyethyleneimine, potassium nitrate, polyethylene glycol, potassium permanganate, sodium hydroxide, ethylenediamine, and polyvinylpyrrolidone.

[0043] Optionally, the amount of the structure guiding agent added is 6 w / v% to 180 w / v.

[0044] Furthermore, in step S3, the high-temperature reaction is carried out at 180–220°C for 8–24 hours.

[0045] Furthermore, the morphology of the iron oxide nanoparticles obtained in S3 is spherical, rod-shaped, polyhedral, hollow sphere, pine cone-shaped, or honeycomb-shaped, with a size of 30–400 nm.

[0046] Example 1: An efficient method for preparing iron oxide nanoparticles with controllable morphology and particle size.

[0047] Includes the following steps:

[0048] S1. Weigh 50g of ferric chloride and dissolve it in 100mL of 1,2-propanediol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 50% ferric chloride solution.

[0049] S2. Add 50g of urea (the amount of urea added is 50w / v%) as a structure guide agent, continue to sonicate and stir until dissolved, transfer the resulting liquid to a 500mL polytetrafluoroethylene reactor, seal it, and react at 200℃ for 24h.

[0050] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 10.7 g of hollow spherical Fe3O4 magnetic particles, with a yield of 75%. The magnetic separation time of the magnetic beads was 4 s. See the results below. Figure 1 As can be seen, the microspheres are hollow spheres.

[0051] Example 2: An efficient preparation method for iron oxide nanoparticles with controllable morphology and particle size.

[0052] Includes the following steps:

[0053] S1. Weigh 50g of ferric acetylacetone and dissolve it in 100mL of 1,2-propanediol. Sonicate and stir until the iron salt is completely dissolved to prepare a 50% ferric acetylacetone solution.

[0054] S2. Add 50g of urea (the amount of urea added is 50w / v%) as a structure guide agent, continue to sonicate and stir until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 24h.

[0055] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 8.7 g of pine cone-shaped Fe3O4 magnetic particles, with a yield of 80%. The magnetic separation time of the magnetic beads was 8 s. See the results below. Figure 2 As can be seen, the microspheres are pinecone-shaped.

[0056] Example 3: An efficient preparation method for iron oxide nanoparticles with controllable morphology and particle size.

[0057] Includes the following steps:

[0058] S1. Weigh 50g of ferric sulfate and dissolve it in 100mL of 1,4-butanediol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 50% ferric sulfate solution.

[0059] S2. Add 11g potassium nitrate, 45g sodium hydroxide, and 22g polyethyleneimine as structure guides. Continue sonicating and stirring until dissolved. Transfer the resulting liquid to a reaction vessel, seal it, and react at 100℃ for 8 hours.

[0060] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 16.44 g of polyhedral Fe3O4 magnetic particles, with a yield of 85%. The magnetic separation time of the magnetic beads was 5 seconds. See the results below. Figure 3 As can be seen, the microspheres are polyhedral irregular shapes.

[0061] Example 4: An efficient method for preparing iron oxide nanoparticles with controllable morphology and particle size.

[0062] Includes the following steps:

[0063] S1. Weigh 50g of potassium ferrocyanide and dissolve it in 100mL of 1,6-hexanediol. Sonicate and stir until the iron salt is completely dissolved to prepare a 50% potassium ferrocyanide solution.

[0064] S2. Add 110g of potassium nitrate as a structure guide agent, continue sonication and stirring until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 100℃ for 8 hours.

[0065] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 7.42 g of nanorod-shaped Fe3O4 magnetic particles, with a yield of 81%. The magnetic separation time of the magnetic beads was 7 s. See the results below. Figure 4 As can be seen, the microspheres are in the shape of nanorods.

[0066] Example 5: An efficient preparation method for iron oxide nanoparticles with controllable morphology and particle size.

[0067] Includes the following steps:

[0068] S1. Weigh 50g of ferrocene and dissolve it in 100mL of diethylene glycol. Sonicate and stir until the iron salt is completely dissolved to prepare a 50% ferrocene solution.

[0069] S2. Add 30g PEG 2000 and 150g anhydrous sodium acetate as structure guides, continue sonicating and stirring until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 8h.

[0070] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 16.6 g of spherical Fe3O4 magnetic particles, with a yield of 80%. The magnetic separation time of the magnetic beads was 12 s. See the results below. Figure 5 As can be seen, the microspheres are spherical.

[0071] Example 6: An efficient method for preparing iron oxide nanoparticles with controllable morphology and particle size.

[0072] Includes the following steps:

[0073] S1. Weigh 50g of ferric nitrate and dissolve it in 100mL of glycerol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 50% ferric nitrate solution.

[0074] S2. Add 20g KMnO4 and 80g sodium citrate as structure guides, continue sonicating and stirring until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 100℃ for 8 hours.

[0075] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 13.1 g of honeycomb-shaped Fe3O4 magnetic particles, with a yield of 82%. The magnetic separation time of the magnetic beads was 19 s. See the results below. Figure 6 As can be seen, the microspheres are honeycomb-shaped.

[0076] Example 7: An efficient preparation method for iron oxide nanoparticles with controllable morphology and particle size.

[0077] Includes the following steps:

[0078] S1. Weigh 100g of ferric chloride and dissolve it in 100mL of ethylene glycol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 100% ferric chloride solution.

[0079] S2. Add 72g of anhydrous sodium acetate, 50mL of ethylenediamine, and 10g of polyvinylpyrrolidone as structure guides. Continue sonicating and stirring until dissolved. Transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 12h.

[0080] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 22.8 g of 30-50 nm spherical Fe3O4 magnetic particles, with a yield of 79.6%. The magnetic separation time of the magnetic beads was 11 s. See the results below. Figure 7 As can be seen, the microspheres are spherical.

[0081] Example 8: An efficient method for preparing iron oxide nanoparticles with controllable morphology and particle size.

[0082] Includes the following steps:

[0083] S1. Weigh 100g of ferric sulfate and dissolve it in 100mL of ethylene glycol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 100% ferric sulfate solution.

[0084] S2. Add 70g of anhydrous sodium acetate and 30g of sodium citrate as structure guides, continue sonicating and stirring until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 10h.

[0085] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 31.7 g of 120-170 nm spherical Fe3O4 magnetic particles, with a yield of 82%. The magnetic separation time of the magnetic beads was 12 s. See the results below. Figure 8 As can be seen, the microspheres are spherical.

[0086] Example 9: An efficient preparation method for iron oxide nanoparticles with controllable morphology and particle size.

[0087] Includes the following steps:

[0088] S1. Weigh 100g of ferric nitrate and dissolve it in 100mL of ethylene glycol. Sonicate and stir until the ferric salt is completely dissolved to prepare a 100% ferric nitrate solution.

[0089] S2. Add 100g of anhydrous sodium acetate and 20g of sodium citrate as structure guides, continue sonicating and stirring until dissolved, transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 8 hours.

[0090] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 25.6 g of 220-270 nm spherical Fe3O4 magnetic particles, with a yield of 80%. The magnetic separation time of the magnetic beads was 13 s. See the results below. Figure 9 As can be seen, the microspheres are spherical.

[0091] Example 10: An efficient method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size.

[0092] Includes the following steps:

[0093] S1. Weigh 100g of potassium ferrocyanide and dissolve it in 100mL of ethylene glycol. Sonicate and stir until the iron salt is completely dissolved to prepare a 100% potassium ferrocyanide solution.

[0094] S2. Add 180g of anhydrous sodium acetate, 30g of sodium citrate, and 6g of PEG 2000 as a structure guide agent. Continue to sonicate and stir until dissolved. Transfer the resulting liquid to a reaction vessel, seal it, and react at 200℃ for 10h.

[0095] S3. After the reaction was completed, the reaction vessel was cooled to room temperature. Once the solution showed clear stratification, the supernatant was removed. The supernatant was washed alternately with anhydrous ethanol and deionized water until it became clear. The black precipitate in the vessel was collected and dried in a vacuum drying oven at 60℃ for 12 hours, yielding 15.6 g of 350-400 nm spherical Fe3O4 magnetic particles, with a yield of 85%. The magnetic separation time of the magnetic beads was 14 s. See the results below. Figure 10 As can be seen, the microspheres are spherical.

[0096] Comparative Example 1: Preparation of Ferric Oxide Nanoparticles

[0097] Add 1.30g FeCl3·6H2O and 0.40g sodium citrate dihydrate to 20mL ethylene glycol until completely dissolved;

[0098] Then add 2.40g NaAc while stirring. Stir the mixture vigorously for 30 minutes until it is thoroughly mixed.

[0099] The mixture was then transferred to a 100 mL polytetrafluoroethylene-lined container and sealed in a stainless steel reactor. The high-pressure reactor was heated to 200 °C and maintained at this temperature for 10 h. The reaction was then stopped, and the mixture was allowed to cool to room temperature. The black product was washed three times with ethanol and deionized water, and the black precipitate was collected and dried in a vacuum oven at 60 °C for 12 h to obtain 0.148 g of magnetic beads, with a yield of 40%. The magnetic separation time of the magnetic beads was 20 s. The results are shown below. Figure 11 .

[0100] Comparative Example 2: Preparation of Ferric Oxide Nanoparticles

[0101] Weigh 1.35g FeCl3·6H2O, add it to 40mL of ethylene glycol, and stir to dissolve it;

[0102] Then add 3.6g NaAc and 1.0g polyethylene glycol 2000, and continue stirring for 0.5h;

[0103] The obtained solution was transferred to a 100 mL hydrothermal reactor, which was then placed in a drying oven at 200 °C to initiate the hydrothermal reaction. After 8 hours of reaction, the reactor was removed and allowed to cool to room temperature. The black precipitate was collected and dried in a vacuum oven at 60 °C for 12 hours to obtain 0.135 g of magnetic beads, with a yield of 35%. The magnetic separation time of the magnetic beads was 22 s. The results are shown below. Figure 12 .

[0104] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size, characterized in that, Includes the following steps: S1. Dissolve the iron salt in the polyol, and sonicate and stir until the iron salt no longer dissolves; the concentration of the iron salt after dissolving in the polyol is 50 w / v %~100 w / v %%. S2. Add the structure guiding agent, continue stirring, transfer the resulting liquid to the reactor, seal, and react at high temperature; S3. After the reaction is complete, the product is naturally cooled to room temperature. The resulting black product is washed several times with deionized water and ethanol to obtain iron oxide nanoparticles.

2. The method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, In S1, the iron salt is at least one of ferric acetylacetone, potassium ferrocyanide, ferrocene, ferric sulfate, ferric nitrate, and ferric chloride.

3. The method for preparing iron oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, In S1, the polyol is at least one selected from ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and glycerol.

4. The method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, In S2, the structure directing agent is at least one of sodium citrate, anhydrous sodium acetate, urea, polyethyleneimine, potassium nitrate, polyethylene glycol, potassium permanganate, sodium hydroxide, ethylenediamine, and polyvinylpyrrolidone.

5. The method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, In step S2, the amount of the structure guiding agent added is 6 w / v % to 180 w / v %.

6. The method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, In S2, the high-temperature reaction is carried out at 180–220°C for 8–24 hours.

7. The method for preparing iron(III) oxide nanoparticles with controllable morphology and particle size according to claim 1, characterized in that, The morphology of the iron oxide nanoparticles obtained in S3 is spherical, rod-shaped, polyhedral, hollow sphere, pinecone-shaped, and honeycomb-shaped; the size is 30-400 nm.

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