Method for synthesizing monodisperse Cu2O polycrystalline nano-microspheres at low temperature and normal pressure

Abstract

The invention discloses a method for synthesizing monodisperse Cu2O polycrystalline nano microspheres at low temperature and normal pressure. The method is based on the idea of improving supersaturation and molecular collision frequency based on high concentration and overcoming reaction kinetic energy barriers, and comprises two processes of one-time'explosive 'homogeneous nucleation and'crystal nucleus' aggregation growth. The preparation method comprises the following steps: preparing a high-concentration mixed solution of a copper source, water and polyol, adding a proper amount of ligand, and uniformly mixing; in the reaction process, an alkali solution is dropwise added into a mixed solution, a reducing agent is dropwise added at one time under the condition of 10-30 DEG C, centrifugation and washing are conducted, and the monodisperse Cu2O polycrystalline nanometer microspheres are obtained. According to the method, the Cu2O polycrystalline nano-microspheres with the target particle size can be obtained by controlling the adding amount of the complexing agent in the mixed solution. The synthesis method is safe, environment-friendly, high in yield and easy for industrial production.

Description

Technical Field

[0001] This invention relates to a method for synthesizing monodisperse Cu2O polycrystalline nanospheres with adjustable particle size under low temperature and normal pressure conditions, belonging to the field of Cu2O polycrystalline microsphere preparation technology. Background Technology

[0002] P-type semiconductor Cu2O possesses excellent catalytic activity and a high refractive index (theoretical refractive index 2.7). It is a low-cost, non-toxic transition metal oxide, and its unique optical and electrical properties make it applicable in catalysts, batteries, structural colors, and other fields. The controllable synthesis of Cu2O nanoparticles is quite challenging due to their rich crystal structures and surface properties. Traditionally, the construction of polycrystalline cuprous oxide nanospheres often relies on precise and demanding experimental conditions, such as high-temperature, high-pressure hydrothermal / solvothermal methods (temperatures greater than 150℃) (see Chen W, Li L, Peng Q, et al. Nano Research, 2012, 5(5): 320-326.), strict oxygen-free environments, or the use of template agents. These methods require extremely high thermodynamic and kinetic control of crystal growth, and the processes are complex and difficult to scale up. Currently, the preparation of Cu2O polycrystalline nanospheres with tunable particle size at low temperature and ambient pressure, ranging in size from several hundred nanometers, remains a significant challenge.

[0003] Domestic and international researchers have conducted extensive research on the preparation of monodisperse Cu2O polycrystalline microspheres at low temperature and ambient pressure. Although some progress has been made, the process still needs improvement. Pang et al. (see Pang M, Zeng H C. Langmuir, 2010, 26(8): 5963-5970.) used hydrazine hydrate in 2-propanol to reduce copper nitrate to Cu2O polycrystalline microspheres at room temperature. The reducing agent used was too strong, the morphology was difficult to control, and it was toxic and not easy to produce on a large scale. Yang et al. (see Yang S, Zhang D, Lin G. Journal of Materials Chemistry, 2011, 22.) used insoluble cuprous chloride as an intermediate to slow down the hydrolysis and condensation rate of copper ions during the reduction of copper chloride with ascorbic acid, and prepared Cu2O polycrystalline microspheres with a size of 150-250 nm. The particle size of Cu2O polycrystalline microspheres synthesized by this method is limited. In addition, Cu2O polycrystalline microspheres can be synthesized by introducing biomass polyphenol tannic acid as a precursor (see patent CN 107473258 A). However, this method requires the prior synthesis of copper hydroxide, followed by centrifugation and washing, in preparation for the subsequent synthesis of Cu2O polycrystalline microspheres, making the experimental process relatively complex. Therefore, further exploration of a method for preparing Cu2O polycrystalline microspheres under low temperature and ambient pressure is of great significance. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for synthesizing monodisperse Cu₂O polycrystalline nanospheres at low temperature and ambient pressure. The resulting monodisperse Cu₂O polycrystalline nanospheres have tunable particle size. This method is based on the idea of ​​overcoming the reaction kinetic energy barrier by increasing supersaturation and molecular collision frequency through high concentration. It includes two processes: a single "burst" homogeneous nucleation and the aggregation and growth of the nuclei. This is achieved by increasing the Cu content of the reaction solution. 2+ Depending on the concentration of the reducing agent, homogeneous nucleation occurs rapidly in the reaction solution; subsequently, the aggregation and growth of these nuclei are guided by polymeric ligands. The polyol in the reaction system not only possesses reducing properties but also ensures an appropriate viscosity, controlling the nucleation and growth kinetics of Cu₂O polycrystalline microspheres and creating favorable conditions for the directional attachment of primary nanocrystals into well-defined polycrystalline nanospheres. Following this synthesis method, the target particle size can be precisely obtained by changing the ratio of the complexing agent to the copper source in the reaction solution. The microspheres exhibit good particle size uniformity and a polycrystalline structure.

[0005] This invention provides a method for synthesizing monodisperse Cu₂O polycrystalline nanospheres at low temperature and ambient pressure, comprising the following steps:

[0006] 1) Using inorganic copper salt as the copper source and a mixed solution of organic polyol and water as the solvent, a copper ion complexing agent and a polymeric ligand are added and mixed thoroughly to obtain a mixed solution, which is used as the reaction solution; the polymeric ligand is used to control the morphology; the copper ions (Cu... 2+ Complexing agents are used to control the particle size of Cu2O polycrystalline nanospheres;

[0007] 2) At a low temperature (10-30℃), add alkaline solution to the mixed solution obtained in step 1), react for 5-20 min, then add reducing agent solution, react for 50-90 min (preferably 1 h) to obtain monodisperse Cu2O polycrystalline nanospheres;

[0008] The Cu 2+ The complexing agent is selected from salts of multiple carboxylate groups or amine ligands;

[0009] Cu in solvent 2+ The concentration is 0.09M-0.23M;

[0010] Cu 2+ The molar ratio with the complexing agent is 0.5-3.0:1;

[0011] Cu 2+ The mass ratio of the polymeric ligand to the polymeric ligand is 1.4-0.56:1.

[0012] Furthermore, in the above technical solution, in step 1), the mass ratio of water to organic polyol in the mixed solution of organic polyol and water is 2:1-5:12, preferably 2:1-5:9.

[0013] Furthermore, in the above technical solution, in step 1), the copper source is one of copper acetate, copper sulfate, copper nitrate, and copper chloride.

[0014] Furthermore, in the above technical solution, in step 1), the organic polyol is one or a mixture of two of ethylene glycol, glycerol, 1,3-propanediol, butanediol, polyethylene glycol, and pentaerythritol.

[0015] Furthermore, in the above technical solution, in step 1), the complexing agent is mainly selected from one or two of trisodium citrate, potassium sodium tartrate, sodium oxalate, and disodium ethylenediaminetetraacetate.

[0016] Furthermore, in the above technical solution, in step 1), the polymeric ligand is one or a mixture of two of polyvinylpyrrolidone, polyacrylamide, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

[0017] Furthermore, in the above technical solution, in step 1), the molecular weight of the polyvinylpyrrolidone is K25-K100, preferably K60-K100.

[0018] Furthermore, in the above technical solution, in step 1), Cu 2+ The mass ratio of the polymeric ligand to the polymeric ligand is 1.4-0.56:1.

[0019] Furthermore, in the above technical solution, in step 1), the copper source and Cu... 2+ The complexing agent is dissolved in the solvent, and then the polymeric ligand is added and fully dissolved to obtain a homogeneous mixed solution.

[0020] Furthermore, in the above technical solution, in step 1), the mixing is carried out under stirring conditions, the stirring rate before adding the polymer ligand is 300-600 rpm, and the stirring rate after adding the polymer ligand is 400-700 rpm.

[0021] Furthermore, in the above technical solution, in step 2), the reducing agent is one of glucose, ascorbic acid, and sodium borohydride.

[0022] Furthermore, in the above technical solution, in step 2), the concentration of the reducing agent solution is 1.1-2.2M, and the concentration of the reducing agent solution is preferably 2.0-2.15M.

[0023] Furthermore, in the above technical solution, in step 2), the volume ratio of the reaction solution to the reducing agent solution is 15:4-15:2, and the preferred volume ratio of the reaction solution to the reducing agent solution is 5:1-7:1.

[0024] Furthermore, in the above technical solution, in step 2), the reducing agent solution is added by dripping at a rate of 0.5-0.9 ml / min.

[0025] Furthermore, in the above technical solution, in step 2), the alkaline solution is one of sodium hydroxide solution, potassium hydroxide solution, tetramethylammonium hydroxide solution, and ammonia water, preferably sodium hydroxide solution.

[0026] Furthermore, in the above technical solution, in step 2), the concentration of the alkaline solution is 6-10M.

[0027] Furthermore, in the above technical solution, in step 2), the volume ratio of the reaction solution to the alkali solution is 2:1-15:1, and the volume ratio of the reaction solution to the alkali solution is 7.5:1-15:1.

[0028] Furthermore, in the above technical solution, in step 2), the alkaline solution is added by dripping.

[0029] Furthermore, in the above technical solution, the polymeric ligand is preferably polyvinylpyrrolidone with a molecular weight of K60-K100. The sodium hydroxide concentration is preferably 6-10M, and the reducing agent concentration is preferably 2.0-2.15M.

[0030] Furthermore, in the above technical solution, in step 2), the reaction is carried out under stirring conditions. The stirring rate before adding the reducing agent solution is 400-600 rpm, and the stirring rate after adding the reducing agent solution is greater than 500 rpm and less than or equal to 1500 rpm.

[0031] Furthermore, in the above technical solution, the method specifically includes the following steps:

[0032] Add the copper source (0.09-0.23M) and complexing agent (0.036M-0.5M) to a mixed solvent of water and polyol (mass ratio of water to polyol is 2:1-5:9), and stir to mix (stirring speed is 300-600 rpm). After dissolution, add the polymeric ligand polyvinylpyrrolidone (0.03mM-0.12mM) and stir until homogeneous (stirring speed is 400-700 rpm) to obtain a mixed solution. At a temperature of 10-30℃, add 5-15 mL of 6-10M sodium hydroxide solution to the above mixed solution and stir gently (stirring speed is 400-600 rpm). After reacting for 10 min, a reducing solution (concentration of 2.0-2.15 M) was added at a certain dropping rate (dropping rate range of 0.5-0.9 ml / min), and the mixture was stirred vigorously (stirring speed greater than 500 and less than or equal to 1500 rpm) for 1 h. After washing with water three or more times, centrifugation was performed, and the mixture was dried to obtain solid Cu2O polycrystalline nanospheres.

[0033] Furthermore, in the above technical solution, the particle size of the monodisperse Cu2O polycrystalline nanospheres is 100-500 nm.

[0034] Monodisperse Cu2O polycrystalline nanospheres synthesized by the above method.

[0035] This invention provides a method for synthesizing monodisperse Cu₂O polycrystalline nanospheres with tunable particle size under low temperature and ambient pressure, by controlling only the Cu 2+ The molar ratio with the complexing agent can be adjusted to control the particle size of monodisperse Cu2O polycrystalline nanospheres from 100 to 500 nm. This process is simple, uses safe and environmentally friendly raw materials, has high yield, low cost, good repeatability, and is easy to industrialize.

[0036] Beneficial effects of the invention

[0037] This invention discloses a method for preparing Cu₂O polycrystalline nanospheres with precisely controllable particle size under low temperature and ambient pressure. According to the synthesis method, Cu₂O nanospheres can be precisely designed with a pre-set target particle size. 2+ The addition ratio of complexing agent was adjusted to obtain Cu₂O polycrystalline nanospheres with the target particle size. Typically, under low-temperature conditions, crystals tend to form thermodynamically stable single-crystal structures due to the Ostwald ripening mechanism. This invention increases the Cu content in the reaction solution... 2+ The concentrations of the reducing agent and the polymeric ligand polyvinylpyrrolidone (PVP) are controlled, with the PPVP ligand acting as a morphology-directing agent. High concentrations increase supersaturation and molecular collision frequency, overcoming the reaction kinetic energy barrier, thus enabling the synthesis of uniform Cu₂O polycrystalline nanospheres at low temperatures. Simultaneously, this method significantly expands the tunable particle size range, which can be adjusted from 100 nm to 500 nm. Attached Figure Description

[0038] Figure 1 The image shows the X-ray diffraction pattern of the Cu2O polycrystalline nanospheres obtained in Example 1.

[0039] Figure 2 This is a transmission electron microscope (TEM) image of the Cu₂O polycrystalline nanospheres obtained in Example 1.

[0040] Figure 3 This is a scanning electron microscope image of the Cu2O polycrystalline nanospheres obtained in Example 1.

[0041] Figure 4 This is a particle size distribution diagram of the Cu2O polycrystalline nanospheres obtained in Example 1.

[0042] Figure 5 This is a scanning electron microscope image of the Cu2O polycrystalline nanospheres obtained in Example 2.

[0043] Figure 6 This is a scanning electron microscope image of the Cu2O polycrystalline nanospheres obtained in Example 3. Detailed Implementation

[0044] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available or can be prepared by conventional methods.

[0045] Example 1

[0046] A method for preparing monodisperse Cu₂O polycrystalline nanospheres, comprising the following steps:

[0047] 1) Weigh 2.8g of copper acetate (0.1M concentration) and 2.5g of trisodium citrate (0.057M concentration), add them to a mixed solution of water and ethylene glycol (volume ratio of water to ethylene glycol is 5:9), and stir until completely dissolved (stirring speed is 400 rpm) to obtain a homogeneous solution; then add 5g of polyvinylpyrrolidone K80 (0.032mM concentration) to the solution and stir (stirring speed is 600 rpm) to fully dissolve the polyvinylpyrrolidone in the solution to obtain a homogeneous reaction solution.

[0048] 2) Quickly transfer the well-stirred reaction solution to a three-necked flask and maintain the water bath temperature at 20°C. Add NaOH solution (8M, 10mL) while stirring at 500rpm. After reacting for 10min, add ascorbic acid solution (2.12M, 20mL) dropwise while stirring at 1000rpm at a rate of 0.8mL / min. Stop the reaction after 1h.

[0049] 3) The reaction system was centrifuged while hot, washed with water 3 times, dried at 60℃, and ground to obtain solid Cu2O nanospheres with a particle size of 150±5nm.

[0050] The obtained monodisperse Cu₂O nanospheres were subjected to XRD tests, and their crystal structure was analyzed, such as... Figure 1 As shown, the diffraction peak positions and relative intensities of the obtained product are consistent with the standard cubic Cu₂O pattern, with the standard card being JCPDS NO.05-0667. Furthermore, the absence of other impurity peaks in the figure demonstrates that the product possesses high crystalline phase purity.

[0051] observe Figure 2 The transmission electron microscopy (TEM) images show that the synthesized Cu₂O nanospheres have a polycrystalline structure.

[0052] observe Figure 3 Scanning electron microscopy revealed that the prepared microspheres exhibited excellent monodispersity, good spherical morphology, and well-defined particle size distribution data. Figure 4 Calculations show that its particle size distribution coefficient is less than 5%, indicating a narrow particle size distribution.

[0053] Example 2

[0054] A method for preparing monocrystalline Cu₂O polycrystalline nanospheres, comprising the following steps:

[0055] 1) Weigh 2.8g of copper acetate (0.1M concentration) and 3g of trisodium citrate (0.073M concentration), add them to a mixed solution of water and ethylene glycol (volume ratio of water to ethylene glycol is 5:9), and stir (stirring speed is 400rpm) until completely dissolved to obtain a homogeneous solution; then add 5g of polyvinylpyrrolidone K80 (0.032mM concentration) to the solution, and stir (stirring speed is 600rpm) to fully dissolve the polyvinylpyrrolidone in the solution to obtain a homogeneous reaction solution.

[0056] 2) Quickly transfer the well-stirred reaction solution to a three-necked flask and maintain the water bath temperature at 20°C. Add NaOH solution (8M, 10mL) while stirring at 500rpm. After reacting for 10min, add ascorbic acid solution (2.12M, 20mL) dropwise while stirring at 1000rpm at a rate of 0.8mL / min. Stop the reaction after 1h.

[0057] 3) The reaction system was centrifuged while hot, washed with water three times, dried at 60℃, and ground to obtain solid Cu2O nanospheres with a particle size of 200±5nm.

[0058] observe Figure 5 Based on scanning electron microscopy characterization and particle size distribution statistics, the particle size distribution coefficient was calculated to be less than 4%, indicating a narrow particle size distribution.

[0059] Example 3

[0060] A method for preparing monodisperse Cu₂O polycrystalline nanospheres, comprising the following steps:

[0061] 1) Weigh 2.8g of copper acetate (0.1M concentration) and 4g of trisodium citrate (0.10M concentration), add them to a mixed solution of water and ethylene glycol (volume ratio of water to ethylene glycol is 5:9), and stir (stirring speed is 400rpm) until completely dissolved to obtain a homogeneous solution; then add 5g of polyvinylpyrrolidone K80 (0.032mM concentration) to the solution, and stir (stirring speed is 600rpm) to fully dissolve the polyvinylpyrrolidone in the solution to obtain a homogeneous reaction solution.

[0062] 2) Quickly transfer the well-stirred reaction solution to a three-necked flask and maintain the water bath temperature at 20°C. Add NaOH solution (8M, 10mL) while stirring at 500rpm. After reacting for 10min, add ascorbic acid solution (2.12M, 20mL) dropwise while stirring at 1000rpm at a rate of 0.8mL / min. Stop the reaction after 1h.

[0063] 3) The reaction system was centrifuged while hot, washed with water 3 times, dried at 60℃, and ground to obtain solid Cu2O nanospheres with a particle size of 410±5nm.

[0064] observe Figure 6 Based on scanning electron microscopy characterization and particle size distribution statistics, the particle size distribution coefficient was calculated to be less than 5%, indicating a narrow particle size distribution.

[0065] Examples 4-6

[0066] The inorganic copper salt used in Example 1 was replaced with copper sulfate, copper nitrate and copper chloride respectively, while the corresponding molar amounts remained unchanged. Cu2O polycrystalline nanospheres with particle sizes of about 165nm, 180nm and 240nm were prepared respectively, with a particle size distribution coefficient of less than 5%.

[0067] Example 7

[0068] 1) Weigh 2.8g of copper sulfate (0.23M concentration) and 1.5g of disodium ethylenediaminetetraacetate (0.05M concentration), add them to a mixed solvent of water and glycerol (mass ratio of water to glycerol is 2:1), and stir until completely dissolved (stirring speed is 400 rpm) to obtain a homogeneous solution; then add 3g of polyvinylpyrrolidone K80 (0.036mM concentration) to the solution and stir (stirring speed is 600 rpm) to fully dissolve the polyvinylpyrrolidone in the solution to obtain a homogeneous reaction solution.

[0069] 2) Quickly transfer the well-stirred reaction solution to a three-necked flask and maintain the water bath temperature at 20°C. Add NaOH solution (8M, 10mL) at a stirring speed of 500rpm. After reacting for 10min, add glucose solution (2.12M, 20mL) dropwise at a stirring speed of 1000rpm at a dropping rate of 0.6mL / min. Stop the reaction after 1h.

[0070] 3) The reaction system was centrifuged while hot, washed with water 3 times, dried at 60℃, and ground to obtain solid Cu2O nanospheres with a particle size of 230±5nm.

[0071] Example 8

[0072] 1) Weigh 2.8g of copper nitrate (0.136M concentration) and 3.5g of sodium oxalate (0.237M concentration), add them to a mixed solvent of water and neopentyl glycol (mass ratio of water to neopentyl glycol is 5:6), and stir until completely dissolved (stirring speed is 400 rpm) to obtain a homogeneous solution; then add 5g of polyvinylpyrrolidone (molecular weight K60, 0.113mM) to the solution and stir (stirring speed is 600 rpm) to fully dissolve the polyvinylpyrrolidone in the solution to obtain a homogeneous reaction solution.

[0073] 2) Quickly transfer the well-stirred reaction solution to a three-necked flask and maintain the water bath temperature at 20°C. Add NaOH solution (8M, 10mL) at a stirring speed of 500rpm. After reacting for 10min, add glucose solution (2.12M, 20mL) dropwise at a stirring speed of 1000rpm at a dropping rate of 0.6mL / min. Stop the reaction after 1h.

[0074] 3) The reaction system was centrifuged while hot, washed with water 3 times, dried at 60℃, and ground to obtain uniform monodisperse Cu2O polycrystalline nanospheres with a particle size of 245±5nm.

[0075] Examples 9-11

[0076] By replacing the mass ratio of water to ethylene glycol in Example 1 with 1:1, 2:3, and 5:7, respectively, monodisperse Cu2O polycrystalline nanospheres with particle sizes of approximately 365 nm, 235 nm, and 180 nm can be prepared.

[0077] Examples 12-14

[0078] By replacing the concentration of disodium ethylenediaminetetraacetate (EDTA) used in Example 7 with 0.036 M, 0.042 mM, and 0.075 mM, respectively, monodisperse Cu2O polycrystalline nanospheres with particle sizes of approximately 120 nm, 175 nm, and 420 nm can be prepared.

[0079] Examples 15-17

[0080] By replacing the concentration of sodium oxalate in Example 8 with 0.2M, 0.25M, and 0.5M respectively, monodisperse Cu2O polycrystalline nanospheres with particle sizes of approximately 180nm, 256nm, and 455nm can be prepared respectively.

Claims

1. A method for synthesizing monodisperse Cu₂O polycrystalline nanospheres at low temperature and ambient pressure, characterized in that: Includes the following steps: 1) Using inorganic copper salt as the copper source, a mixed solution of organic polyol and water as the solvent, copper ion complexing agent and polymeric ligand are added and mixed evenly to obtain a mixed solution, which is used as the reaction solution. 2) At 10-30℃, add alkaline solution to the mixed solution obtained in step 1), react for 5-20 min, then add reducing agent solution, react for 50-90 min, and obtain monodisperse Cu2O polycrystalline nanospheres; The copper ion complexing agent is selected from salts of multiple carboxylate groups or amine ligands; Cu 2+ The mass ratio of the polymeric ligand to the ligand is 1.4-0.56:1; Cu 2+ The molar ratio with the complexing agent is 0.5-3.0:1; Cu in solvent 2+ The concentration is 0.09M-0.23M.

2. The method according to claim 1, characterized in that: The copper source is one of copper acetate, copper sulfate, copper nitrate, and copper chloride; the organic polyol is one or a mixture of two of ethylene glycol, glycerol, 1,3-propanediol, butanediol, polyethylene glycol, and pentaerythritol.

3. The method according to claim 1, characterized in that: The polymeric ligand is one or a mixture of two of polyvinylpyrrolidone, polyacrylamide, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide; the complexing agent is selected from one or two of trisodium citrate, sodium potassium tartrate, sodium oxalate, and disodium ethylenediaminetetraacetate.

4. The method according to claim 1, characterized in that: In a mixed solution of organic polyol and water, the mass ratio of water to organic polyol is 2:1 to 5:

12.

5. The method according to claim 1, characterized in that: The alkaline solution is one of sodium hydroxide solution, potassium hydroxide solution, tetramethylammonium hydroxide solution, or ammonia water; the reducing agent is one of glucose, ascorbic acid, or sodium borohydride.

6. The method according to claim 1, characterized in that: The concentration of the alkaline solution is 6-10M, and the volume ratio of the reaction solution to the alkaline solution is 2:1-15:1; the concentration of the reducing agent solution is 1.1-2.2M, and the volume ratio of the reaction solution to the reducing agent solution is 15:4-15:

2.

7. The method according to claim 1, characterized in that: The reducing agent solution is added dropwise at a rate of 0.5-0.9 ml / min.

8. The method according to claim 1, characterized in that: The reaction is carried out under stirring conditions. The stirring rate before adding the reducing agent solution is 400-600 rpm, and the stirring rate after adding the reducing agent solution is greater than 500 rpm and less than or equal to 1500 rpm.

9. The method according to claim 1, characterized in that: The monodisperse Cu2O polycrystalline nanospheres have a particle size of 100-500 nm.

10. Monodisperse Cu₂O polycrystalline nanospheres synthesized by the method according to any one of claims 1-9.

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