Method for preparing indium oxide powder material

Abstract

The invention discloses a method for preparing an indium oxide powder material, which comprises the following steps: with indium nitrate and 1, 4-naphthalic acid as reaction raw materials, adding a surface modifier accounting for 0-20% of the total mass of the reaction raw materials into an organic solvent system to prepare an indium-based metal organic framework material; separating, washing and drying the indium-based metal organic framework material to obtain an indium-based metal organic framework precursor; and annealing the indium-based metal organic framework precursor to obtain the indium oxide powder material. According to the preparation method, 1, 4-NDC is selected as an organic bridging ligand, the concentration of the 1, 4-NDC and the dosage of a surface modifier are regulated and controlled, an In-MOF structure with a special morphology can be formed through induction, and the morphology can be kept intact through adjustment of the annealing temperature and parameters; the morphology controllability of the indium oxide particles allows crystal face exposure and charge transfer paths of the indium oxide particles to be customized, and the performance of the indium oxide particles in optoelectronic equipment, energy storage and photocatalysis is optimized.

Description

Technical Field

[0001] This invention relates to the field of powder material preparation technology, and in particular to a method for preparing indium oxide powder material. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of organic-inorganic hybrid functional materials characterized by high porosity and large specific surface area. Their pore size and morphology can be easily tuned by selecting different metal ions and organic bridging ligands. Transition metal-organic frameworks (MOFs) are a class of porous materials that have emerged in recent years, possessing rich and controllable structures and large specific surface areas. They have been widely used in catalysis, gas storage, adsorption separation, and other fields, thus becoming a research focus in recent years. Furthermore, due to the diverse organic ligands and varying binding states of metal ions in MOFs, the morphological appearance of their products exhibits a wide range of possibilities. High-temperature calcination and topological transformation methods can convert MOFs into corresponding metal oxide forms, providing an effective method for preparing oxides with special morphologies. This invention, by controlling the ligand concentration and the effect of surface modifiers, yields a novel indium-based MOF structure with a unique morphology. By adjusting the annealing temperature and parameters, topologically transformed indium oxide particles with well-preserved morphology are obtained, representing a method for preparing indium oxide with a special morphology. Summary of the Invention

[0003] This invention provides a method for preparing indium oxide powder materials, the specific technical solution of which is as follows: A method for preparing indium oxide powder material includes the following steps: Indium-based metal-organic framework materials were prepared by adding a surface modifier accounting for 0-20% by mass of the total amount of reactants in an organic solvent system using indium nitrate and 1,4-naphthalenedicarboxylic acid as reactants. After separating, washing and drying the indium-based metal-organic framework material, an indium-based metal-organic framework precursor is obtained. Indium-based metal-organic framework precursors are annealed to obtain indium oxide powder materials.

[0004] Preferably, in step a: The molar ratio of 1,4-naphthoic acid to indium nitrate is (28~56):(15~60). 1,4-Naphthalenedicarboxylic acid is expressed in mol, and organic solvent is expressed in L. The ratio of 1,4-naphthalenedicarboxylic acid to organic solvent is (0.28~0.56):(40~90). Indium nitrate is expressed in mol, and organic solvent is expressed in L. The ratio of indium nitrate to organic solvent is (0.15~0.6):(40~90).

[0005] Preferably: The organic solvent system is selected from N,N-dimethylformamide or N,N-dimethylformamide / ethanol mixture, wherein the mass ratio of N,N-dimethylformamide to ethanol in the N,N-dimethylformamide / ethanol mixture is (3~8):1; The surface modifier is selected from at least one of PVP, PEG-modified CTAB, and Gemini-type quaternary ammonium salt.

[0006] Preferably: In step a, the indium-based metal-organic framework material is prepared by a solvothermal reaction, wherein the conditions for the solvothermal reaction include: reacting at 100~140℃ for 4~36 h; In step c, the annealing process specifically includes: placing the indium-based metal-organic framework precursor in a muffle furnace and annealing it at 500°C for 2 hours with a heating rate of 1~5°C / min.

[0007] Preferably, the solvothermal reaction employs a staged heating method, specifically including the following steps: i. Crystal nuclei are formed after reacting at 90~110℃ for 0.5~2 h; ii. Increase the temperature to 120-140℃ at a heating rate of 0.2-1℃ / min, and react for 4-12 h; iii. Keep warm at 120~140℃ for 12~24 h.

[0008] Preferably, in step a, the surface modifier is added in stages, specifically including the following steps: i. Add 50%~70% of the surface modifier at the initial stage of the reaction to promote crystal nucleation; ii. After reacting for 1 to 2 h, add the remaining surface modifier at a dropping rate of 0.05 to 0.2 mL / min.

[0009] Preferably: The separation is performed by centrifugation at a speed of 8000~10000 rpm for 3~10 min. The washing process includes sequential washing with N,N-dimethylformamide, ethanol, and deionized water, wherein the ethanol washing is performed at least three times. The drying process is carried out in a vacuum drying oven at 50-70°C for 8-15 hours.

[0010] Preferably, in step c: The annealing process adopts a step-by-step heating method, specifically including the following steps: holding at 150~250℃ for 0.5~2h to remove water of crystallization, holding at 300~400℃ for 1~3h, and then holding at 400~500℃ for 1~3h. The annealing process is carried out in a mixed atmosphere, which is a combination of O2 and N2, wherein the volume ratio of O2 to N2 is 1:(1~5), and the heating rate is controlled at 0.5~5℃ / min. The annealing process also includes an in-situ doping step, specifically: introducing SnCl4 vapor at 300~400℃, wherein the carrier gas is N2, and the flow rate is 30~70 mL / min.

[0011] Preferably, the PEG-modified CTAB is prepared by the following steps: Monomethoxy polyethylene glycol and p-toluenesulfonyl chloride were reacted in anhydrous pyridine / dichloromethane in an ice bath at 0°C for 2 h, and then stirred at room temperature for 12 h. The product was purified by column chromatography to obtain mPEG-OTs. mPEG-OTs were reacted with NaN3 in DMF at 60°C for 24 h. The reaction solution was desalted by dialysis and lyophilized to obtain azide-functionalized PEG. Hexadecyltrimethylammonium bromide was dissolved in anhydrous DMF, propargyl bromide and potassium carbonate were added, and the reaction was carried out at 80 °C for 48 h under nitrogen protection. After the reaction was completed, the inorganic salt was removed by filtration, the mixture was concentrated under reduced pressure, precipitated with diethyl ether, and recrystallized to obtain alkynyl quaternary ammonium salt. Under nitrogen protection, azide-functionalized PEG and alkynyl quaternary ammonium salt were dissolved in a tert-butanol / water (1:1) mixed solvent; CuSO4·5H2O and sodium ascorbate were added sequentially, and the mixture was stirred at room temperature for 24-48 h; the reaction solution was subjected to copper removal by chelating resin, small molecules were removed by dialysis, and the product was obtained by lyophilization.

[0012] Preferably, the Gemini-type quaternary ammonium salt is prepared by the following steps: Tetramethylalkyldiamine and bromoalkyl are mixed evenly at a molar ratio of 1:(2.2~2.5) and placed in a microwave reaction tube; under nitrogen protection, the microwave power is set to 200~400 W, the temperature is controlled at 80~120℃, and the reaction time is 10~40 minutes. After the reaction is complete, the product is cooled to room temperature and recrystallized 2-3 times with ethyl acetate or acetone. The product is then dried under vacuum at 50°C for 24 hours to obtain the final product.

[0013] The method for preparing indium oxide powder materials provided by this invention can induce the formation of In-MOF structures with special morphologies by selecting 1,4-NDC as an organic bridging ligand and controlling its concentration and the amount of surface modifier. The adjustment of annealing temperature and parameters can ensure that the morphology is well preserved. Its morphology controllability allows for the customization of the crystal face exposure and charge transport path of indium oxide particles, optimizing its performance in optoelectronic devices (such as ITO thin films), energy storage (lithium battery electrodes) and photocatalysis. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0015] Figure 1 Scanning electron microscope image of the indium-based MOF precursor material prepared in Example 7 provided for this embodiment; Figure 2 Scanning electron microscope image of the indium-based MOF precursor material prepared in Example 11 provided for this embodiment; Figure 3 Scanning electron microscope image of the indium oxide particulate material prepared in Example 3 provided for this embodiment; Figure 4 Scanning electron microscope image of the indium oxide particulate material prepared in Example 13 provided for this embodiment; Figure 5 Scanning electron microscope image of the indium oxide particulate material prepared in Example 14 provided for this embodiment; Figure 6 X-ray diffraction pattern of the indium-based MOF precursor material prepared in Example 7 of this embodiment; Figure 7 X-ray diffraction pattern of the indium-based MOF precursor material prepared in Example 11 provided for this embodiment; Figure 8 X-ray diffraction pattern of indium oxide particulate material prepared in Example 3 of this embodiment. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0017] This invention provides a method for preparing indium oxide powder material, comprising the following steps: Indium-based metal-organic framework materials were prepared by adding a surface modifier accounting for 0-20% by mass of the total reactants in an organic solvent system using indium nitrate and 1,4-naphthalenedicarboxylic acid as reactants.

[0018] Indium-based metal-organic framework (MOF) precursors are obtained by separating, washing, and drying the indium-based MOF material.

[0019] Indium-based metal-organic framework precursors are annealed to obtain indium oxide powder materials.

[0020] The method for preparing indium oxide powder materials provided in this embodiment can induce the formation of In-MOF structures with special morphologies by selecting 1,4-NDC as an organic bridging ligand and controlling its concentration and the amount of surface modifier. The adjustment of annealing temperature and parameters can ensure that the morphology is well preserved. Its morphology controllability allows for the customization of the crystal face exposure and charge transport path of indium oxide particles, optimizing its performance in optoelectronic devices (such as ITO thin films), energy storage (lithium battery electrodes) and photocatalysis.

[0021] Furthermore, in step a: The molar ratio of 1,4-naphthoic acid to indium nitrate is (28~56):(15~60).

[0022] 1,4-Naphthalenedicarboxylic acid is expressed in mol, and organic solvent is expressed in L. The ratio of 1,4-naphthalenedicarboxylic acid to organic solvent is (0.28~0.56):(40~90).

[0023] Indium nitrate is expressed in mol, and organic solvent is expressed in L. The ratio of indium nitrate to organic solvent is (0.15~0.6):(40~90).

[0024] Furthermore: The organic solvent system is selected from N,N-dimethylformamide or N,N-dimethylformamide / ethanol mixture, and the mass ratio of N,N-dimethylformamide to ethanol in the N,N-dimethylformamide / ethanol mixture is (3~8):1.

[0025] The surface modifier is selected from at least one of PVP, PEG-modified CTAB, and Gemini-type quaternary ammonium salt.

[0026] Polyvinylpyrrolidone (PVP) interacts with indium ions or the carboxyl groups of 1,4-naphthalenedicarboxylic acid through coordination or hydrogen bonding of the carbonyl group of its pyrrolidone ring. It selectively adsorbs onto specific crystal faces, inhibits the growth rate of those crystal faces, and thus induces anisotropic growth to form rod-shaped, sheet-like, or porous In-MOF precursors.

[0027] However, in the indium nitrate + 1,4-naphthalenedicarboxylic acid (1,4-NDC) system used in this embodiment, ordinary hexadecyltrimethylammonium bromide (CTAB), as a traditional cationic surfactant, is widely used in the synthesis of many metal-organic frameworks. However, its strong electrostatic interaction is poorly matched with the large hydrophobic aromatic ring of 1,4-NDC, which easily leads to local supersaturation during the crystal nucleation stage, rapid disordered crystal growth, and thus serious agglomeration, irregular morphology, and byproducts such as In(OH)3. The yield and specific surface area are not ideal.

[0028] To overcome the above-mentioned defects, this embodiment introduces two targeted modification schemes: (1) Polyethylene glycol (PEG) modified CTAB: By grafting PEG segments onto the quaternary ammonium head group or alkyl chain of CTAB, the hydrophilicity and steric hindrance effect of the surfactant are significantly enhanced. The flexible long chain of PEG improves the solubility and dispersion stability of modified CTAB in DMF / ethanol mixed solvent, while reducing the electrostatic density of the head group and avoiding excessive electrostatic attraction caused by ordinary CTAB; the PEG segments can also have weak π-π or hydrophobic interactions with the naphthalene ring of 1,4-NDC, further optimizing the selective adsorption of crystal faces. This modification makes the crystal growth process more moderate and orderly, significantly reduces agglomeration, improves the uniformity and thermal stability of the In-MOF precursor, and finally obtains indium oxide particles with well-preserved morphology after annealing.

[0029] (2) Gemini-type quaternary ammonium salt surfactants: Compared with traditional surfactants with a single head and a single tail, Gemini-type quaternary ammonium salts have a unique structure with two hydrophilic head groups, two hydrophobic tail chains, and spacer groups. Their critical micelle concentration (CMC) is usually reduced by 1 to 3 orders of magnitude, resulting in stronger surface activity and more stable micelle morphology. This structure can form a denser template layer in solution, which can more effectively control the orientation and growth direction of crystal nuclei. It is especially suitable for large-size rigid ligand (such as 1,4-NDC) systems and can promote the formation of precursors with hierarchical porous or regular polyhedral structures. After annealing and conversion, the specific surface area and porosity of indium oxide particles are significantly improved.

[0030] The introduction of the two modified surfactants mentioned above not only overcomes the inherent defects of ordinary cationic surfactants in this system, but also achieves fine control of the morphology of In-MOF through the synergistic effect of hydrophilic-hydrophobic balance, steric hindrance and template effect, providing a key guarantee for the subsequent preparation of high-performance indium oxide powder materials by topological transformation.

[0031] Furthermore: In step a, the indium-based metal-organic framework material is prepared by a solvothermal reaction. The solvothermal reaction conditions include reacting at 100~140℃ for 4~36 h.

[0032] In step c, the annealing process specifically includes: placing the indium-based metal-organic framework precursor in a muffle furnace and annealing it at 500°C for 2 hours with a heating rate of 1~5°C / min.

[0033] Furthermore, the solvothermal reaction employs a staged heating method, specifically including the following steps: i. Crystal nuclei are formed after reacting at 90~110℃ for 0.5~2 h.

[0034] ii. Increase the temperature to 120-140℃ at a heating rate of 0.2-1℃ / min and react for 4-12 h.

[0035] iii. Keep warm at 120~140℃ for 12~24 h.

[0036] The process involves three stages: the first stage (90-110℃) forms uniform crystal nuclei at a lower temperature, inhibits indium nitrate hydrolysis (reducing In(OH)3 byproducts), and provides a stable initial structure for the growth of MOFs with special morphologies; the second stage (heating to 120-140℃ at a rate of 0.2-1℃ / min) regulates crystal growth along a specific direction by a slow heating rate, allowing the modifier to be adsorbed more uniformly at progressively higher temperatures; and the third stage (holding at 120-140℃) extends the reaction time, ensuring complete coordination of 1,4-NDC, enhancing the thermal stability and pore structure of the MOF framework, and reducing the loss of unreacted raw materials.

[0037] Furthermore, in step a, the surface modifier is added in stages, specifically including the following steps: i. Add 50% to 70% of surface modifier at the beginning of the reaction to promote crystal nucleation.

[0038] ii. After reacting for 1 to 2 h, add the remaining surface modifier at a dropping rate of 0.05 to 0.2 mL / min.

[0039] Among them, adding a modifier at the beginning of the reaction can effectively control the formation of crystal nuclei; after 1 to 2 hours of reaction, the crystal nuclei begin to grow in a specific direction. At this time, the remaining modifier is added at a specific dropping rate, and the crystal growth direction is controlled by the dynamic concentration gradient.

[0040] Furthermore: The separation was performed by centrifugation at a speed of 8000~10000 rpm for 3~10 min.

[0041] The washing process includes washing with N,N-dimethylformamide, ethanol, and deionized water in sequence, with the ethanol washing performed at least three times.

[0042] Drying is carried out in a vacuum drying oven at 50~70℃ for 8~15 hours.

[0043] Furthermore, in step c: The annealing process adopts a step-by-step heating method, specifically including the following steps: holding at 150~250℃ for 0.5~2 h to remove water of crystallization, holding at 300~400℃ for 1~3 h, and then holding at 400~500℃ for 1~3 h.

[0044] The annealing process is carried out in a mixed atmosphere, which is a combination of O2 and N2, with a volume ratio of O2 to N2 of 1:(1~5), and the heating rate is controlled at 0.5~5℃ / min.

[0045] The annealing process also includes an in-situ doping step, specifically: introducing SnCl4 vapor at 300~400℃, wherein the carrier gas is N2, and the flow rate is 30~70 mL / min.

[0046] In the stepwise heating method: the low-temperature dehydration stage can slowly remove the water of crystallization and adsorbed solvent in In-MOF, avoiding framework stress damage caused by rapid heating; in the intermediate-temperature decomposition stage, 1,4-NDC and PVP are gradually decomposed into CO2 and H2O, avoiding the violent gas release from high-temperature one-time decomposition that damages the structure; the high-temperature crystallization stage can ensure the formation of indium oxide crystals, while avoiding excessively high temperatures that lead to excessively large grains or increased oxygen defects.

[0047] Mixed atmospheres can control the oxidation rate, reduce carbon residue, and protect crystal morphology. In-situ doping steps can stabilize the crystal structure and reduce pore collapse during the MOF decomposition stage through Sn doping.

[0048] Furthermore, PEG-modified CTAB was prepared through the following steps: Monomethoxy polyethylene glycol and p-toluenesulfonyl chloride were reacted in anhydrous pyridine / dichloromethane in an ice bath at 0°C for 2 h, and then stirred at room temperature for 12 h. The product was purified by column chromatography to obtain mPEG-OTs. mPEG-OTs were reacted with NaN3 in DMF at 60°C for 24 h. The reaction solution was desalted by dialysis and lyophilized to obtain azide-functionalized PEG.

[0049] Hexadecyltrimethylammonium bromide was dissolved in anhydrous DMF, propargyl bromide and potassium carbonate were added, and the reaction was carried out at 80°C for 48 h under nitrogen protection. After the reaction was completed, the inorganic salt was removed by filtration, the mixture was concentrated under reduced pressure, precipitated by diethyl ether, and recrystallized to obtain alkynyl quaternary ammonium salt.

[0050] Under nitrogen protection, azide-functionalized PEG and alkynyl quaternary ammonium salt were dissolved in a tert-butanol / water (1:1) mixed solvent; CuSO4·5H2O and sodium ascorbate were added sequentially, and the mixture was stirred at room temperature for 24-48 h; the reaction solution was subjected to copper removal by chelating resin, small molecules were removed by dialysis, and the product was obtained by lyophilization.

[0051] Among them, the preparation of polyethylene glycol modified hexadecyltrimethylammonium bromide (PEG-CTAB) adopts the click chemistry (CuAAC) coupling method. Compared with the traditional substitution or amidation route, this method has significant advantages such as mild reaction conditions (room temperature), high selectivity, no by-products, high grafting efficiency, and effective removal of copper catalyst.

[0052] Specifically, monomethoxy polyethylene glycol (mPEG-OH) is first converted to mPEG-N3 via a two-step toluenesulfonation-azidation reaction; simultaneously, the quaternary ammonium head group of CTAB is functionalized into an alkyne derivative (CTAB-alkyne); subsequently, an azide-alkyne cycloaddition reaction is carried out under Cu(I) catalysis to form a stable 1,2,3-triazole ring linker. This triazole ring not only serves as a rigid spacer group but also provides additional hydrogen bonds and π-π interaction sites, further enhancing the synergistic adsorption capacity of modified CTAB and the 1,4-NDC ligand.

[0053] Compared to traditional thioether or ester bond linkages, the click chemistry route avoids the risk of quaternary ammonium salt degradation under alkaline conditions. At the same time, the triazole ring has better thermal stability than flexible chain bonds and is less prone to breakage during subsequent solvothermal and annealing processes, thus better maintaining the continuous regulatory effect of surface modifiers on crystal faces.

[0054] Furthermore, Gemini-type quaternary ammonium salts are prepared via the following steps: Tetramethylalkyldiamine and bromoalkyl are mixed evenly at a molar ratio of 1:(2.2~2.5) and placed in a microwave reaction tube; under nitrogen protection, the microwave power is set to 200~400 W, the temperature is controlled at 80~120℃, and the reaction time is 10~40 minutes.

[0055] After the reaction is complete, the product is cooled to room temperature and recrystallized 2-3 times with ethyl acetate or acetone. The product is then dried under vacuum at 50°C for 24 hours to obtain the final product.

[0056] Specifically, under solvent-free or minimal co-solvent conditions, tetramethylalkyldiamine and bromoalkane are directly mixed, and the uniform and rapid heating characteristics of microwaves complete the double-end quaternization reaction within 10–40 minutes. The non-contact energy transfer of microwaves avoids the temperature gradient and local overheating in traditional heating, significantly reducing side reactions (incomplete single-end quaternization or thermal degradation), and the purity and yield of the product are generally higher than those of traditional methods.

[0057] The resulting Gemini-type quaternary ammonium salt has an extremely low critical micelle concentration and stronger synergistic surface activity. Its biheaded structure can form a more stable vesicle-like or rod-like micelle template, effectively suppressing disordered aggregation during crystal growth. The flexible adjustment of the spacer group further optimizes the head-to-group spacing, making it more compatible with the molecular size of 1,4-NDC, and promoting the directional execution of the ligand-metal coordination process.

[0058] Specific embodiments are provided below. These embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Example 1

[0059] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0060] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed diverse morphologies and non-uniform sizes. Example 2

[0061] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 40 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0062] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were not smooth. Example 3

[0063] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 50 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0064] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed agglomeration, but the morphology remained intact. Example 4

[0065] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 80 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0066] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were of non-uniform size. Example 5

[0067] 0.56 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0068] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were long and thin with an uneven morphology. Example 6

[0069] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.15 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0070] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were relatively uniform. Example 7

[0071] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 4 h at a rotation speed of 350 rpm.

[0072] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were uniform in size and evenly dispersed. Example 8

[0073] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 8 h at a rotation speed of 350 rpm.

[0074] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed diverse morphologies and uneven dispersion. Example 9

[0075] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 50 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 100 °C for 12 h at a rotation speed of 350 rpm.

[0076] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed a large number of agglomerated particles. Example 10

[0077] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 50 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 140 °C for 12 h at a rotation speed of 350 rpm.

[0078] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the morphology was inhomogeneous and uneven. Example 11

[0079] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC), 0.1 g of PVP, and 0.3 mmol of indium nitrate hydrate were dissolved in 50 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0080] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles had uniform morphology and smooth surfaces. Example 12

[0081] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC), 0.2 g of PVP, and 0.3 mmol of indium nitrate hydrate were dissolved in 50 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0082] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were unevenly dispersed and exhibited agglomeration. Example 13

[0083] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 4 h at a rotation speed of 350 rpm.

[0084] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 2℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were relatively dispersed and of uneven size. Example 14

[0085] 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 4 h at a rotation speed of 350 rpm.

[0086] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 5℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed that the particles were more dispersed and of uneven size. Example 15

[0087] Monomethoxy polyethylene glycol (mPEG-OH, 5 mmol) with a molecular weight of 2000 was reacted with p-toluenesulfonyl chloride (TsCl, 6 mmol) in anhydrous pyridine / dichloromethane (1:1 volume ratio) at 0 °C in an ice bath for 2 h, followed by stirring at room temperature for 12 h. The product was purified by column chromatography to obtain mPEG-OTs. Subsequently, mPEG-OTs (4 mmol) was reacted with NaN3 (20 mmol) in DMF at 60 °C for 24 h, and after desalting by dialysis (MWCO 1000 Da) and lyophilization, mPEG-N3 was obtained.

[0088] Separately, hexadecyltrimethylammonium bromide (CTAB, 4 mmol) was dissolved in anhydrous DMF, and propargyl bromide (6 mmol) and potassium carbonate (8 mmol) were added. The reaction was carried out at 80 °C for 48 h under nitrogen protection. The inorganic salts were removed by filtration, the solution was concentrated under reduced pressure, precipitated with diethyl ether, and recrystallized to obtain alkynyl-functionalized CTAB (CTAB-alkyne).

[0089] mPEG-N3 (4 mmol) and CTAB-alkyne (4 mmol) were dissolved in a tert-butanol / water (1:1) mixture, and CuSO4·5H2O (0.2 mmol) and sodium ascorbate (0.4 mmol) were added. The mixture was stirred for 36 h at room temperature under nitrogen protection. The reaction solution was subjected to copper removal by chelating resin, dialyzed (MWCO 3500 Da) to remove small molecules, and lyophilized to obtain PEG-modified CTAB.

[0090] Take 0.12 g of the above-mentioned PEG-modified CTAB, dissolve 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate in a mixed solvent of 50 mL N,N-dimethylformamide and 10 mL ethanol (DMF:ethanol mass ratio 5:1), add the surface modifier, and stir the solution in a magnetic stirrer for 15 min to ensure homogeneity. Transfer the solution to an oil bath, equip it with a reflux condenser, and react at 120 °C for 12 h at a rotation speed of 350 rpm.

[0091] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12 h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 2℃ / min to 500℃ for 2 h to finally obtain indium oxide particles. Scanning results showed that the particles had regular morphology, a uniform rod-like structure, good dispersibility, and a narrow size distribution. Example 16

[0092] N,N,N',N'-tetramethyl-1,6-hexanediamine (1.0 equivalent, 10 mmol) and bromododecane (C 12 H 25 Mix Br (2.4 equivalents, 24 mmol) and place in a microwave-safe reaction tube under nitrogen protection. Microwave power 300 W, temperature programmed: first hold at 80 °C for 5 min, then increase to 110 °C for 25 min. After the reaction, cool, recrystallize the crude product three times with hot ethyl acetate, and dry under vacuum (50 °C, 24 h) to give a white solid Gemini-type quaternary ammonium salt (yield 92%).

[0093] Take 0.10 g of the above-mentioned Gemini-type quaternary ammonium salt, dissolve 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate in a mixed solvent of 50 mL N,N-dimethylformamide and 10 mL ethanol (DMF:ethanol mass ratio 5:1), add the surface modifier, and stir the solution in a magnetic stirrer for 15 min to ensure homogeneity. Transfer the solution to an oil bath, equip it with a reflux condenser, and react at 120 °C for 12 h at a rotation speed of 350 rpm.

[0094] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12 h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 2℃ / min to 500℃ for 2 h to finally obtain indium oxide particles. Scanning results showed that the particles exhibited a regular porous lamellar structure, were uniformly dispersed, had smooth surfaces, and showed very little agglomeration.

[0095] Comparative Example 1 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.6 mmol of indium nitrate hydrate were dissolved in 30 mL of N,N-methylformamide. The solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0096] The solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 1℃ / min to 500℃ for 2h to finally obtain indium oxide particles. Scanning results showed no obvious morphology.

[0097] Comparative Example 2 0.28 mmol of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 0.3 mmol of indium nitrate hydrate were dissolved in a mixed solvent of 50 mL of N,N-dimethylformamide and 10 mL of ethanol (DMF:ethanol mass ratio 5:1). 0.10 g of hexadecyltrimethylammonium bromide (CTAB) was added, and the solution was stirred in a magnetic stirrer for 15 min to ensure homogeneity. The solution was then transferred to an oil bath, fitted with a reflux condenser, and reacted at 120 °C for 12 h at a rotation speed of 350 rpm.

[0098] The reaction solution was washed several times with ethanol, centrifuged, and the lower precipitate was dried in a vacuum drying oven at 10℃ / h to 60℃ for 12 h to obtain the indium-based MOF precursor. The indium-based MOF precursor was then annealed in a muffle furnace at 2℃ / min to 500℃ for 2 h to finally obtain indium oxide particles. Scanning results showed severe particle agglomeration, irregular morphology, uneven size, and obvious blocky accumulation.

[0099] The table below shows the yield and purity data of the indium oxide powder materials prepared in Examples 1-16 and Comparative Examples 1-2: This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing indium oxide powder material, characterized in that, Includes the following steps: Indium-based metal-organic framework materials were prepared by adding a surface modifier accounting for 0-20% by mass of the total amount of reactants in an organic solvent system using indium nitrate and 1,4-naphthalenedicarboxylic acid as reactants. After separating, washing and drying the indium-based metal-organic framework material, an indium-based metal-organic framework precursor is obtained. Indium-based metal-organic framework precursors are annealed to obtain indium oxide powder materials.

2. The method according to claim 1, characterized in that, In step a): The molar ratio of 1,4-naphthoic acid to indium nitrate is (28~56):(15~60). 1,4-Naphthalenedicarboxylic acid is expressed in mol, and organic solvent is expressed in L. The ratio of 1,4-naphthalenedicarboxylic acid to organic solvent is (0.28~0.56):(40~90). Indium nitrate is expressed in mol, and organic solvent is expressed in L. The ratio of indium nitrate to organic solvent is (0.15~0.6):(40~90).

3. The method according to claim 1, characterized in that: The organic solvent system is selected from N,N-dimethylformamide or N,N-dimethylformamide / ethanol mixture, wherein the mass ratio of N,N-dimethylformamide to ethanol in the N,N-dimethylformamide / ethanol mixture is (3~8):1; The surface modifier is selected from at least one of PVP, PEG-modified CTAB, and Gemini-type quaternary ammonium salt.

4. The method according to claim 1, characterized in that: In step a), the indium-based metal-organic framework material is prepared by a solvothermal reaction, wherein the conditions for the solvothermal reaction include: reacting at 100~140℃ for 4~36 h; In step c), the annealing process specifically includes: placing the indium-based metal-organic framework precursor in a muffle furnace and annealing it at 500°C for 2 hours with a heating rate of 1~5°C / min.

5. The method according to claim 4, characterized in that, The solvothermal reaction employs a segmented heating method, specifically including the following steps: (i) Crystal nuclei are formed after reacting at 90~110℃ for 0.5~2 h; (ii) Increase the temperature to 120-140℃ at a heating rate of 0.2-1℃ / min and react for 4-12 h; (iii) Keep warm at 120~140℃ for 12~24 h.

6. The method according to claim 1, characterized in that, In step a), the surface modifier is added in stages, specifically including the following steps: (i) Add 50% to 70% of surface modifier at the beginning of the reaction to promote crystal nucleation; (ii) After 1 to 2 h of reaction, the remaining surface modifier is added at a dropping rate of 0.05 to 0.2 mL / min.

7. The method according to claim 1, characterized in that: The separation is performed by centrifugation at a speed of 8000~10000 rpm for 3~10 min. The washing process includes sequential washing with N,N-dimethylformamide, ethanol, and deionized water, wherein the ethanol washing is performed at least three times. The drying process is carried out in a vacuum drying oven at 50-70°C for 8-15 hours.

8. The method according to claim 1, characterized in that, In step c): The annealing process adopts a step-by-step heating method, specifically including the following steps: holding at 150~250℃ for 0.5~2 h to remove water of crystallization, holding at 300~400℃ for 1~3 h, and then holding at 400~500℃ for 1~3 h. The annealing process is carried out in a mixed atmosphere, which is a combination of O2 and N2, wherein the volume ratio of O2 to N2 is 1:(1~5), and the heating rate is controlled at 0.5~5℃ / min. The annealing process also includes an in-situ doping step, specifically: introducing SnCl4 vapor at 300~400℃, wherein the carrier gas is N2, and the flow rate is 30~70 mL / min.

9. The method according to claim 3, characterized in that, The PEG-modified CTAB was prepared through the following steps: Monomethoxy polyethylene glycol and p-toluenesulfonyl chloride were reacted in anhydrous pyridine / dichloromethane in an ice bath at 0°C for 2 h, and then stirred at room temperature for 12 h. The product was purified by column chromatography to obtain mPEG-OTs. mPEG-OTs were reacted with NaN3 in DMF at 60°C for 24 h. The reaction solution was desalted by dialysis and lyophilized to obtain azide-functionalized PEG. Hexadecyltrimethylammonium bromide was dissolved in anhydrous DMF, propargyl bromide and potassium carbonate were added, and the reaction was carried out at 80 °C for 48 h under nitrogen protection. After the reaction was completed, the inorganic salt was removed by filtration, the mixture was concentrated under reduced pressure, precipitated with diethyl ether, and recrystallized to obtain alkynyl quaternary ammonium salt. Under nitrogen protection, azide-functionalized PEG and alkynyl quaternary ammonium salt were dissolved in a tert-butanol / water (1:1) mixed solvent; CuSO4·5H2O and sodium ascorbate were added sequentially, and the mixture was stirred at room temperature for 24-48 h; the reaction solution was subjected to copper removal by chelating resin, small molecules were removed by dialysis, and the product was obtained by lyophilization.

10. The method according to claim 3, characterized in that, The Gemini-type quaternary ammonium salt was prepared by the following steps: Tetramethylalkyldiamine and bromoalkyl are mixed evenly at a molar ratio of 1:(2.2~2.5) and placed in a microwave reaction tube; under nitrogen protection, the microwave power is set to 200~400 W, the temperature is controlled at 80~120℃, and the reaction time is 10~40 minutes. After the reaction is complete, the product is cooled to room temperature and recrystallized 2-3 times with ethyl acetate or acetone. The product is then dried under vacuum at 50°C for 24 hours to obtain the final product.

Images