ZnO particles with different morphologies and preparation method thereof

Abstract

The invention relates to ZnO particles with different morphologies and a preparation method thereof. According to the invention, a simple direct precipitation method is adopted, the ZnO particles with controllable morphology can be obtained by adjusting the reaction time, temperature and pH value, and the preparation method is simple, easy to operate, green and environment-friendly. The synthesized ZnO particles are uniform in dispersion, uniform in particle size and regular in morphology, and start from the center, a plurality of one-dimensional hexagonal cones are finally stacked and self-assembled to form a 3D polygonal flower-shaped structure. Wherein along with the increase of the reaction pH, the morphology of the obtained ZnO particles is evolved into a transition state of particles with rough surfaces from a flower shape, and then the lamellar flower-shaped morphology with regular morphology is generated.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, in particular to ZnO particles with different morphologies and preparation methods thereof. Background Art

[0002] Zinc oxide (ZnO) is a II-VI group wide bandgap semiconductor material with a bandgap of 3.37 eV at room temperature, corresponding to a response wavelength of about 380 nm. The exciton binding energy is as high as 60 meV, which enables ZnO to undergo exciton absorption and recombination at room temperature, and its optical gain coefficient is as high as 300 cm -1 ZnO has the advantages of small size, simple preparation, narrow response band, high sensitivity, etc. Nano-scale ZnO has more excellent properties, such as piezoelectric effect, near-ultraviolet photoelectric effect, biocompatibility, transparent conductivity, etc. It is used in the fields of piezoelectric materials, ultraviolet light excitation detection, solar cells, gas sensors, etc. These different applications make ZnO materials have extensive research value.

[0003] Zinc oxide crystals have polar characteristics, which leads to their rich nano-morphology. Different structures such as nanowires, nanotubes, nanobelts, nanosheets, nanorings, nanoflowers, and nanohelical structures each have their own specific uses, making the morphology and structural control of ZnO of great significance. The structure and morphology of zinc oxide materials are closely related to the performance of the material. For example, the flower-like structure composed of nano-sized zinc oxide rods has a large specific surface area, a mesoporous effect, and excellent performance. At the same time, the physical, chemical, structural and morphological characteristics of ZnO nanostructures mainly depend on their synthesis process. Controlling the morphology of ZnO nanomaterials is still a hot topic in the research field of ZnO materials. At present, there are many methods for preparing ZnO nanomaterials, such as metal organic chemical vapor deposition, hydrothermal method, sol-gel method, electrodeposition method, etc., and the methods used to prepare different types of ZnO nanostructures are different.

[0004] However, further research is still needed to prepare zinc oxide with different morphologies using the same reaction method and to achieve the preparation of ZnO particles with controllable morphologies. Summary of the invention

[0005] Based on the deficiencies of the prior art, the technical problem to be solved by the present invention is to obtain ZnO particles with controllable morphology by adjusting the reaction time, temperature and pH value, and to provide ZnO particles with different morphologies and a preparation method thereof.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing ZnO particles with different morphologies, comprising the following steps:

[0008] (1) dissolving zinc acetate and L-phenylalanine in water to obtain a mixed solution;

[0009] (2) adding an alkaline solution to the mixed solution under stirring to adjust the pH;

[0010] (3) After the pH is adjusted to the target value, the reaction is allowed to stand;

[0011] (4) After the reaction, the solid is collected by centrifugation, washed and dried to obtain the product.

[0012] Preferably, in step (1), the zinc acetate is zinc acetate dihydrate.

[0013] Preferably, in step (1), the molar ratio of zinc acetate to L-phenylalanine is 1:2.

[0014] Preferably, in step (1), the concentration of zinc acetate in the mixed solution is 0.05 mol / L; the concentration of L-phenylalanine in the mixed solution is 0.1 mol / L.

[0015] Preferably, in step (2), the alkaline solution is a NaOH solution; the concentration of the alkaline solution is 1.0 mol / L; and the pH of the mixed solution is adjusted to 9-14.

[0016] Preferably, in step (3), the temperature of the static reaction is from room temperature to 140°C.

[0017] Preferably, in step (3), the standing reaction time is 5-120 min.

[0018] Preferably, in step (4), the centrifugal speed is 10000 rpm, and the centrifugal time is 10 min; ultrapure water and ethanol are used for washing 3 times respectively; the drying temperature is 50° C., and the drying time is 24 h.

[0019] The invention provides a ZnO particle, and the ZnO particle is prepared by the preparation method.

[0020] Preferably, ZnO particles with different morphological characteristics are obtained by regulating the reaction pH in the preparation method; as the reaction pH increases, the morphology of the obtained ZnO particles evolves from a flower-like shape to a transition state with rough particles on the surface, and then generates a lamellar flower-like morphology with regular morphology;

[0021] If the reaction pH in the preparation method is 12, the resulting ZnO particles are self-assembled into a 3D polygonal flower-like structure by stacking several one-dimensional hexagonal pyramids;

[0022] If the reaction pH in the preparation method is 13, the resulting ZnO particles are flower-like structures with rough particles on the surface;

[0023] If the reaction pH in the preparation method is 14, the obtained ZnO particles have a lamellar flower-like structure.

[0024] The technical solution of the present invention achieves the following beneficial technical effects:

[0025] The ZnO particles synthesized by the present invention are evenly dispersed, uniform in particle size, and regular in morphology, presenting a 3D polygonal flower-like structure formed by stacking and self-assembly of multiple one-dimensional hexagonal cones starting from the center. As the reaction pH increases, the morphology of the obtained ZnO particles changes from a flower-like shape to a transition state of particles with rough surfaces, and then generates a regular lamellar flower-like morphology, which has not been synthesized in the prior art.

[0026] The invention can obtain ZnO particles with different morphologies by adjusting the reaction time, temperature and pH value. The invention adopts a simple direct precipitation method to prepare ZnO particles with different morphologies. The preparation method is simple, easy to operate and green and environmentally friendly.

[0027] The ZnO particles with different morphologies obtained by the present invention have good topological effects on the micro-nano structures on the surface of rice leaves. The inlay and adhesion of ZnO particles on the different micro-nano structures on the rice leaf surface are beneficial to the deposition of pesticide droplets, which provides good application prospects for such ZnO particles with bionic morphology in the field of pesticide formulation research and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Morphological images of ZnO particles synthesized under different reaction time conditions in Example 1 of the present invention;

[0029] Figure 2 Morphological images of ZnO particles synthesized under different reaction temperature conditions in Example 1 of the present invention;

[0030] Figure 3 Morphological images of ZnO particles synthesized under different reaction pH conditions in Example 1 of the present invention;

[0031] Figure 4 Morphology of flower-shaped ZnO particles No. 17 obtained in Example 1 of the present invention (scale is 2 μm);

[0032] Figure 5 Morphology of the ZnO particles with a lamellar flower-like morphology obtained with number 19 in Example 1 of the present invention;

[0033] The scale of (a) is 50 μm; the scale of (b) is 2 μm. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and technical effect of the invention of this application clearer, the technical scheme in the embodiment of this application will be clearly and completely described below in conjunction with the drawings in the embodiment of this application. Obviously, the described embodiment is a part of the embodiment of this application, not all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] In view of the technical problems existing in the prior art, the present invention provides a method for preparing ZnO particles with different morphologies, comprising the following steps:

[0036] (1) dissolving zinc acetate and L-phenylalanine in water to obtain a mixed solution;

[0037] (2) adding an alkaline solution to the mixed solution under stirring to adjust the pH;

[0038] (3) After the pH is adjusted to the target value, the reaction is allowed to stand;

[0039] (4) After the reaction, the solid is collected by centrifugation, washed and dried to obtain the product.

[0040] In the step (1), the zinc acetate is zinc acetate dihydrate; the molar ratio of zinc acetate to L-phenylalanine is 1:2; the concentration of zinc acetate in the mixed solution is 0.05 mol / L; the concentration of L-phenylalanine in the mixed solution is 0.1 mol / L;

[0041] In the step (2), the alkaline solution is a NaOH solution; the concentration of the alkaline solution is 1.0 mol / L; the pH of the mixed solution is adjusted to 9-14 (for example, 9, 10, 11, 12, 13 or 14);

[0042] In the step (3), the reaction time is 5-120 minutes (for example, 5 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes, 90 minutes or 120 minutes); the reaction temperature is room temperature to 140°C (for example, 40°C, 60°C, 80°C, 100°C, 120°C or 140°C).

[0043] In a preferred embodiment of the present invention, the static reaction time is 60-120min; the static reaction is carried out at room temperature;

[0044] In the step (4), the centrifugal speed is 10000 rpm and the centrifugal time is 10 min; ultrapure water and ethanol are used for washing 3 times respectively; the drying temperature is 50° C. and the drying time is 24 h.

[0045] The present invention also provides a ZnO particle, wherein the ZnO particle is prepared by the preparation method.

[0046] In a preferred embodiment of the present invention, the ZnO particles are evenly dispersed, have uniform particle size, and have regular morphology.

[0047] In a preferred embodiment of the present invention, ZnO particles with different morphological characteristics are obtained by adjusting the reaction pH in the preparation method;

[0048] If the reaction pH in the preparation method is 12, the resulting ZnO particles are composed of several one-dimensional hexagonal cones starting from the center and eventually stacking and self-assembling into a 3D polygonal flower-like structure;

[0049] If the reaction pH in the preparation method is 13, the resulting ZnO particles are flower-like structures with rough particles on the surface;

[0050] If the reaction pH in the preparation method is 14, the obtained ZnO particles have a lamellar flower-like morphology structure.

[0051] The ZnO particles with different morphologies and the preparation method thereof of the present invention are described in detail below through specific examples.

[0052] Example 1

[0053] This embodiment provides a method for preparing ZnO particles, comprising the following steps:

[0054] (1) dissolving 5 mmol zinc acetate and 10 mmol L-phenylalanine in 100 mL ultrapure water to obtain a mixed solution;

[0055] (2) Under magnetic stirring, add 1.0 mol / L NaOH solution to the mixed solution to adjust the pH to 9-14;

[0056] (3) After the pH is adjusted to the target value, the reaction is allowed to stand at room temperature to 140°C for 5-120 minutes;

[0057] (4) After the reaction, the mixture was centrifuged at 10,000 rpm for 10 min, the solid was collected, washed three times with ultrapure water and ethanol respectively, and dried at 50° C. for 24 h.

[0058] Change the pH of the solution in step (2) (for example, 9, 10, 11, 12, 13 or 14), the reaction temperature in step (3) (for example, 40°C, 60°C, 80°C, 100°C, 120°C or 140°C), and the reaction time (for example, 5 min, 15 min, 30 min, 45 min, 60 min, 90 min or 120 min), and set up a variable test, as shown in Table 1-3.

[0059] Table 1 Effect of reaction time on the morphology of synthesized ZnO particles

[0060]

[0061] The morphology of the ZnO particles obtained from the experiments of groups 1 to 7 was analyzed. The electron microscope images of the ZnO particles are shown in Figure 1 As shown by Figure 1 It can be seen that the nucleation stage occurs when the reaction is carried out for 5-15 minutes, and the growth of ZnO particles is completed after 30 minutes, and the morphology is consistent thereafter.

[0062] Table 2 Effect of reaction temperature on the morphology of synthesized ZnO particles

[0063]

[0064] The morphology of the ZnO particles obtained from the experiments of groups 8-13 was analyzed. The electron microscope images of the ZnO particles are shown in Figure 2 As shown by Figure 2 It can be seen that the morphology of ZnO particles generated under different reaction temperature conditions is consistent, indicating that temperature has no effect on the morphology.

[0065] Table 3 Effect of reaction pH on the morphology of synthesized ZnO particles

[0066]

[0067] The morphology of the ZnO particles obtained from the experiments of groups 14-21 was analyzed. The electron microscope images of the ZnO particles are shown in Figure 3 As shown by Figure 3 It can be seen that the morphology of ZnO particles generated under different pH conditions is obviously different. As the pH increases, the morphology evolves from flower-like to a transitional state of particles with rough surfaces, and then generates a lamellar flower-like morphology with regular morphology.

[0068] Figure 4 Electron micrograph of ZnO particles obtained under the condition of pH 12. Figure 4 It can be seen that when the reaction pH is 12, the resulting ZnO particles are composed of several one-dimensional hexagonal cones starting from the center and eventually stacking and self-assembling into a 3D polygonal flower-like structure;

[0069] Figure 5 Electron micrograph of ZnO particles obtained under the condition of pH 14. Figure 5 It can be seen that when the reaction pH is 14, the obtained ZnO particles have a lamellar flower-like morphology structure.

[0070] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for preparing ZnO particles with different morphologies, characterized in that: The following steps are involved: (1) dissolving zinc acetate and L-phenylalanine in water to obtain a mixed solution; (2) adding an alkaline solution to the mixed solution under stirring to adjust the pH; (3) After the pH is adjusted to the target value, the reaction is allowed to stand; (4) After the reaction, the solid is collected by centrifugation, washed and dried to obtain the product.

2. The preparation method according to claim 1, characterized in that In the step (1), the zinc acetate is zinc acetate dihydrate.

3. The preparation method according to claim 1, characterized in that: In the step (1), the molar ratio of zinc acetate to L-phenylalanine is 1:

2.

4. The preparation method according to claim 1, characterized in that: In the step (1), the concentration of zinc acetate in the mixed solution is 0.05 mol / L; the concentration of L-phenylalanine in the mixed solution is 0.1 mol / L.

5. The preparation method according to claim 1, characterized in that: In the step (2), the alkaline solution is a NaOH solution; the concentration of the alkaline solution is 1.0 mol / L; and the pH of the mixed solution is adjusted to 9-14.

6. The preparation method according to claim 1, characterized in that: In the step (3), the temperature of the static reaction is room temperature to 140°C.

7. The preparation method according to claim 1, characterized in that: In the step (3), the reaction is allowed to stand for 5-120 minutes.

8. The preparation method according to claim 1, characterized in that: In the step (4), the centrifugal speed is 10000 rpm and the centrifugal time is 10 min; ultrapure water and ethanol are used for washing 3 times respectively; the drying temperature is 50° C. and the drying time is 24 h.

9. A ZnO particle, characterized in that: The ZnO particles are prepared by the preparation method according to any one of claims 1 to 9.

10. The ZnO particles according to claim 9, characterized in that By adjusting the reaction pH in the preparation method, ZnO particles with different morphological characteristics are obtained; as the reaction pH increases, the morphology of the obtained ZnO particles changes from a flower-like shape to a transition state with rough particles on the surface, and then to a lamellar flower-like morphology with regular morphology; If the reaction pH in the preparation method is 12, the resulting ZnO particles are self-assembled into a 3D polygonal flower-like structure by stacking several one-dimensional hexagonal pyramids; If the reaction pH in the preparation method is 13, the resulting ZnO particles are flower-like structures with rough particles on the surface; If the reaction pH in the preparation method is 14, the obtained ZnO particles have a lamellar flower-like structure.

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