CN118221153A - Preparation method of ZnO with hierarchical structure through chiral molecular regulation - Google Patents

Abstract

The invention discloses a preparation method of ZnO with a hierarchical structure regulated by a two-handed molecule, comprising: S1, preparing a two-handed molecule solution; S2, adding zinc acetate dihydrate to the two-handed molecule solution and stirring evenly to obtain a mixed solution; S3, adding ammonium carbonate to the mixed solution and stirring for a certain time; S4, placing the mixed solution obtained in step S3 in a polytetrafluoroethylene-lined autoclave for hydrothermal reaction; S5, centrifuging the reaction product obtained in step S4, and then calcining to obtain ZnO with a hierarchical structure. The method induces the crystal face of the crystal to grow along a certain direction through the two-handed molecule to obtain a sheet nanostructure; the induction effect of the chiral molecule forces the obtained sheet nanostructure to curl along a certain axial direction, generating a fine deformation axis, and obtaining a curled spiral nanoflower structure; by changing the polarity of the solvent, the deprotonation degree of the chiral molecule is changed, and the interaction between the chiral molecule and Zn2 ⁺ or the crystal face is indirectly improved, and different curled spiral nanoflower structures are prepared.

Description

Preparation method of ZnO with hierarchical structure regulated by two-handed molecules

Technical Field

The invention belongs to the technical field of nano material synthesis, and in particular relates to a method for preparing ZnO with a hierarchical structure by regulating chiral molecules.

Background technique

Nanocatalysts have a large surface volume percentage due to their small size, different surface bond and electronic states from the interior, and incomplete surface atomic coordination, which increases the number of active sites on the surface. This makes nanocatalysts exhibit many new properties. In reactions, the size, morphology, and surface properties of nanocatalysts have an important influence on their activity and selectivity.

In recent years, it has been found that nano zinc oxide has many special functions in catalysis, optics, magnetism, mechanics, etc. It has important application value in many fields such as ceramics, chemical industry, electronics, optics, biology, medicine, etc., and has special features and uses that ordinary zinc oxide cannot compare with. Nano zinc oxide can be used in ultraviolet light shielding materials, antibacterial agents, fluorescent materials, photocatalytic materials, etc. in the fields of textiles and coatings.

Nano zinc oxide (ZnO) is a white hexagonal crystal or spherical particle with a particle size of less than 100nm, an average particle size of 50nm, a specific surface area of more than ^4m2 /g, good fluidity, extremely high chemical activity, excellent catalytic and photocatalytic activity, and anti-infrared, ultraviolet radiation and sterilization functions. The refinement of nano zinc oxide grains changes its surface electronic structure and crystal structure, resulting in surface effects, volume effects, quantum size effects, macro tunnel effects, high transparency, high dispersibility and other characteristics that macroscopic objects do not have. Nano zinc oxide can also catalyze the photolysis of organic molecules. ZnO with a size of 10 to 25nm can be used for the catalytic photolysis of phenol, and can also be used as a catalyst for the direct synthesis of methanol by CO hydrogenation. Compared with ordinary ZnO, it can significantly improve the CO conversion rate and methanol recovery rate.

However, the microscopic self-assembly behavior of nanomaterials is currently still restricted by the balance driven by Gibbs free energy, and there are thermodynamic limits on the active catalytic sites in nanomaterials.

Therefore, how to regulate the various equilibrium points in the microscopic self-assembly behavior of nanomaterials to produce more active catalytic centers is the current difficulty in improving the efficiency of nanocatalysis and is also the key to improving the catalytic efficiency of nanomaterials.

Summary of the invention

In view of this, some embodiments disclose a method for preparing ZnO having a hierarchical structure by regulating chiral molecules, comprising:

S1. Prepare a chiral molecular solution;

S2, adding zinc acetate dihydrate to the two-handed molecular solution and stirring evenly to obtain a mixed solution;

S3, adding ammonium carbonate to the mixed solution and stirring for a certain period of time;

S4, placing the mixed solution obtained in step S3 in a polytetrafluoroethylene-lined autoclave for hydrothermal reaction;

S5. Centrifugally separate the reaction product obtained in step S4, and then calcine it to obtain ZnO with a hierarchical structure.

Some embodiments disclose a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, wherein step S1 specifically comprises:

The two-handed molecule is added into ultrapure water, a mixed solution of DMF and ultrapure water, a mixed solution of ethanol and ultrapure water, or a mixed solution of ethylene glycol and ultrapure water, and stirred until dissolved to obtain a two-handed molecule solution.

Some embodiments disclose a method for preparing ZnO with a hierarchical structure by regulating the use of chiral molecules, wherein the chiral molecules include methionine and cysteine.

Some embodiments disclose a method for preparing ZnO with a hierarchical structure by regulating a chiral molecule, wherein the methionine is L-methionine and the cysteine is L-cysteine.

In some embodiments, the method for preparing ZnO with a hierarchical structure by regulating chiral molecules is disclosed, wherein the volume ratio of ultrapure water to DMF is 1:1.

In some embodiments, the method for preparing ZnO with a hierarchical structure by regulating chiral molecules is disclosed, wherein the volume ratio of ultrapure water to ethanol is 1:1.

In some embodiments, the method for preparing ZnO with a hierarchical structure by regulating chiral molecules is disclosed, wherein the volume ratio of ultrapure water to ethylene glycol is 1:1.

In some embodiments of the method for preparing ZnO with a hierarchical structure by regulating chiral molecules, in step S3, the stirring reaction time is 30 minutes.

Some embodiments disclose a method for preparing ZnO with a hierarchical structure by regulating chiral molecules, wherein the reaction temperature of the hydrothermal reaction is 120° C. and the reaction time is 2 hours.

Some embodiments disclose a method for preparing ZnO with a hierarchical structure by regulating chiral molecules, wherein the calcination temperature is 550° C. and the calcination time is 6 hours.

The method for preparing ZnO with a hierarchical structure by regulating the chiral molecules disclosed in the embodiment of the present invention comprises the following steps: adding zinc acetate dihydrate and ammonium carbonate to a chiral molecule solution to generate a precipitation reaction, then synthesizing the precipitate in the chiral molecule solution into crystals by a hydrothermal method, and finally calcining the crystals to obtain ZnO with a hierarchical structure. The chiral molecules induce the crystal face to grow in a certain direction to obtain a sheet-like nanostructure; the induction of the chiral molecules forces the obtained sheet-like nanostructure to curl along a certain axial direction, generating a fine deformation axis, and obtaining a nanoflower structure with a curled spiral shape; by changing the polarity of the solvent, the deprotonation degree of the chiral molecules is changed, and the interaction between the chiral molecules and Zn2 ⁺ or the crystal face is indirectly improved, and a nanoflower structure with different curled spiral shapes is prepared; the ZnO with the spiral nanoflower structure has a complex hierarchical structure, a large specific surface area, and can generate more active catalytic center sites, thereby improving the catalytic performance of ZnO.

The method for preparing ZnO with a hierarchical structure by regulating chiral molecules disclosed in the embodiment of the present invention is simple and efficient, has high energy utilization rate, good repeatability and high controllability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a SEM and TEM image of ZnO with a hierarchical structure in Example 1;

FIG2 is a SEM and EDS layered image of ZnO with a hierarchical structure in Example 2;

FIG3 is a SEM and TEM image of ZnO with a hierarchical structure in Example 3;

FIG4 is a SEM and TEM image of ZnO with a hierarchical structure in Example 4;

FIG5 is a SEM image of ZnO with a hierarchical structure in Example 5;

FIG6 is a SEM image of ZnO with a hierarchical structure in Example 6;

FIG. 7 is a SEM image of ZnO with a hierarchical structure in Comparative Example 1;

FIG8 is a SEM image of ZnO with a hierarchical structure in Comparative Example 2.

Detailed ways

The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

The terms "substantially" and "approximately" used herein are used to describe small fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. The numerical data represented or presented in the range format herein are used only for convenience and brevity, and should therefore be flexibly interpreted as including not only the values clearly listed as the limits of the range, but also all independent values or sub-ranges contained in the range. For example, the numerical range of "1-5%" should be interpreted as including not only the clearly listed values of 1% to 5%, but also the independent values and sub-ranges within the range shown. Therefore, independent values such as 2%, 3.5% and 4% and sub-ranges such as 1%-3%, 2%-4% and 3%-5% are included in this numerical range. This principle also applies to the range of only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.

In this document, including in the claims, transitional words such as "comprises," "includes," "with," "having," "containing," "involving," "accommodating," etc. are understood to be open-ended, i.e., meaning "including but not limited to." Only the transitional words "consisting of" and "composed of" are closed transitional words.

In order to better illustrate the content of the present application, numerous specific details are given in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be arbitrarily combined, and the obtained technical solutions belong to the contents disclosed in the embodiments of the present application. It should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like mentioned in the present application indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the technical features and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention, unless it conflicts with the context. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance, unless it conflicts with the context.

In some embodiments, the method for preparing ZnO having a hierarchical structure by regulating the use of a chiral molecule includes:

S1. Prepare a chiral molecular solution;

S2. Add zinc acetate dihydrate to the two-handed polar molecule solution and stir evenly to obtain a uniform and clear mixed solution; generally, zinc acetate dihydrate is added to the two-handed polar molecule solution at 0° C. to prevent zinc acetate dihydrate from being hydrolyzed and oxidized;

S3, adding ammonium carbonate to the mixed solution and stirring the mixture for a certain period of time, wherein the ammonium carbonate is hydrolyzed in the mixed solution to generate a large amount of OH ^- , making the mixed solution weakly alkaline, and Zn ²⁺ in the mixed solution is rapidly precipitated in an alkaline environment to generate basic zinc carbonate;

S4, placing the mixed solution obtained in step S3 in a polytetrafluoroethylene-lined autoclave for hydrothermal reaction recrystallization; the two-handed molecule can act on the coordination bond of ^Zn2+ , and in the process of crystal growth, the two-handed molecule plays the role of surfactant on the one hand, and on the other hand, plays the role of synergistic tuning of the corresponding selectivity at the molecule-crystal surface interface, which can induce the crystal surface to grow along a certain direction to obtain a sheet-like nanostructure, and can also force the obtained sheet-like nanostructure to curl along a certain axial direction to produce a fine deformation axis to obtain a curled spiral nanoflower structure;

S5. Centrifugally separate the reaction product obtained in step S4, and then calcine it to obtain ZnO with a hierarchical structure.

In some embodiments, step S1 specifically includes:

Using ultrapure water, a mixed solution of DMF and ultrapure water, a mixed solution of ethanol and ultrapure water, or a mixed solution of ethylene glycol and ultrapure water as a solvent;

The two-handed molecule is added into ultrapure water, a mixed solution of DMF and ultrapure water, a mixed solution of ethanol and ultrapure water, or a mixed solution of ethylene glycol and ultrapure water, and stirred until dissolved to obtain a two-handed molecule solution.

In some embodiments, the volume of the chiral molecule solution is 15 mL.

In some embodiments, the chiral molecule comprises methionine and cysteine.

In some embodiments, the methionine includes L-methionine and D-methionine.

In some embodiments, the cysteine includes L-cysteine and D-cysteine.

In some embodiments, the chiral molecule is preferably L-methionine or L-cysteine.

In some embodiments, the amount of cysteine added is 100-500 μL, and the concentration of cysteine is 0.02-2 mmol/L.

Preferably, the amount of methionine added is 1 mmol, the amount of cysteine added is 100 μL, the concentration of cysteine is 0.02 mmol/L, the amount of zinc acetate dihydrate added is 0.75-3.0 mmol, and the amount of ammonium carbonate added is 0.5 mmol.

In some embodiments, in the chiral molecule solution in step S1, the concentration of methionine is 0.067 mol/L.

In some embodiments, in the mixed solution in step S2, the concentration of zinc acetate dihydrate is 0.05-0.2 mol/L.

In some embodiments, the concentration of ammonium carbonate in the mixed solution in step S3 is 0.033 mol/L.

In some embodiments, the volume ratio of ultrapure water to DMF is 1: 1. Changing the polarity of the solvent can change the degree of deprotonation of the chiral molecules, which can indirectly improve the interaction between the chiral molecules and Zn ²⁺ or the crystal surface, and prepare nanoflower structures with different coiled helices.

In some embodiments, the volume ratio of ultrapure water to ethanol is 1:1.

In some embodiments, the volume ratio of ultrapure water to ethylene glycol is 1:1.

In some embodiments, in step S3, the stirring reaction time is 30 minutes.

In some embodiments, the reaction temperature of the hydrothermal reaction is 120° C. and the reaction time is 2 h.

In some embodiments, the rotation speed of centrifugal separation is 4500-5500 rpm.

In some embodiments, the calcination temperature is 550° C. and the calcination time is 6 hours.

The technical details are further illustrated below in conjunction with embodiments.

Example 1

FIG. 1 is a SEM and TEM image of ZnO having a hierarchical structure disclosed in Example 1.

This embodiment 1 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine to 15 mL of ultrapure water and stir to dissolve to prepare a chiral molecular solution;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. Areas (a) and (b) in FIG1 are SEM images of ZnO, and areas (c) and (d) in the figure are TEM images of ZnO. As shown in FIG1, the ZnO prepared in this embodiment has an obvious flower ball structure, the diameter of the flower shape is large, and the structure is fragmented.

Example 2

FIG. 2 is a SEM and EDS layered image of the ZnO with a hierarchical structure disclosed in Example 2.

This embodiment 2 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine to 15 mL of ultrapure water and stir to dissolve to prepare a chiral molecular solution;

Add 0.75 mmol zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. In Figure 2, areas (a) and (b) are SEM images of ZnO, and areas (c) and (d) are EDS distribution diagrams of Zn and O elements, respectively. As shown in Figure 2, the ZnO prepared in this embodiment has an obvious flower ball structure, the flower shape has a larger diameter, and the structure is obviously flaky.

Example 3

FIG. 3 is a SEM and TEM image of ZnO with a hierarchical structure disclosed in Example 3.

This embodiment 3 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and DMF, stir and dissolve, and prepare a chiral molecular solution; wherein the volume ratio of ultrapure water to DMF is 1:1;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. Areas (a) and (b) in FIG3 are SEM images of ZnO, and areas (c) and (d) in the figure are TEM images of ZnO. As shown in FIG3, the ZnO prepared in this embodiment has an obvious flower cluster structure, the flower shape has a small diameter, is clustered, and has a petal-like structure.

Example 4

FIG. 4 is an SEM and TEM image of ZnO with a hierarchical structure disclosed in Example 4.

This embodiment 4 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and ethanol, stir and dissolve to prepare a chiral molecular solution; the volume ratio of ultrapure water to ethanol is 1:1;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. Areas (a) and (b) in FIG4 are SEM images of ZnO, and areas (c) and (d) in the figure are TEM images of ZnO. As shown in FIG4, the ZnO prepared in this embodiment has an obvious flower cluster structure, the flower shape has a small diameter, is clustered, and has a petal-like structure.

It can be seen from Examples 1 to 4 that, compared with ZnO produced by a single solvent, ZnO produced by a mixed solvent has a smaller diameter and a more compact distribution.

Example 5

FIG. 5 is a SEM image of ZnO with a hierarchical structure disclosed in Example 5.

This embodiment 5 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and ethanol, stir and dissolve to prepare a chiral molecular solution; the volume ratio of ultrapure water to ethanol is 1:1;

Add 3.0 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm for 10 minutes each time, and then calcined to obtain ZnO with a hierarchical structure. As shown in FIG5 , the ZnO prepared in this example has an obvious flaky structure, with relatively large flakes and clustered together.

It can be seen from Examples 1 to 5 that, compared with Examples 1 to 4, the amount of zinc acetate dihydrate used in this example is larger, and the obtained ZnO flakes are larger and present a stacked shape.

Example 6

FIG. 6 is a SEM image of ZnO with a hierarchical structure disclosed in Example 6.

This embodiment 6 discloses a method for preparing ZnO having a hierarchical structure by regulating a bimanual molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and ethylene glycol, stir and dissolve to prepare a chiral molecular solution; wherein the volume ratio of ultrapure water to ethylene glycol is 1:1;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. As shown in FIG6 , the ZnO prepared in this example has an obvious flower ball structure, with small flakes and clustered together.

Based on Examples 4 to 6, it can be seen that compared with the ZnO prepared using a mixed solution of water and ethanol as a solvent in Examples 4 and 5, the ZnO flakes prepared in this example are smaller and present a flower ball shape.

Comparative Example 1

FIG. 7 is a SEM image of ZnO having a hierarchical structure disclosed in Comparative Example 1. FIG.

This comparative example 1 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and ethanol, stir and dissolve to prepare a chiral molecular solution; the volume ratio of ultrapure water to ethanol is 2:1;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm, each time for 10 minutes, and then calcined to obtain ZnO with a hierarchical structure. As shown in FIG7 , the ZnO prepared in Comparative Example 1 has a disordered stacking structure and uneven distribution.

Comparative Example 2

FIG. 8 is a SEM image of ZnO having a hierarchical structure disclosed in Comparative Example 2.

This comparative example 2 discloses a method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, comprising:

Add 100 μL of 0.02 mmol/L L-cysteine and 1 mmol L-methionine into a mixed solution of 15 mL ultrapure water and ethanol, stir and dissolve to prepare a chiral molecular solution; the volume ratio of ultrapure water to ethanol is 1:2;

Add 1.5 mmol of zinc acetate dihydrate into the two-handed molecular solution at 0°C and stir evenly to obtain a uniform and clear mixed solution;

0.5 mmol of ammonium carbonate was added to the mixed solution and stirred for 30 min;

The mixed solution was placed in a polytetrafluoroethylene-lined autoclave with a volume of 50 mL for hydrothermal reaction at a reaction temperature of 120 °C and a reaction time of 2 h;

The reaction product obtained by the hydrothermal reaction was centrifuged twice at a speed of 5000 rpm for 10 minutes each time, and then calcined to obtain ZnO with a hierarchical structure. As shown in FIG8 , the ZnO prepared in Comparative Example 2 was clustered, with a disordered and irregular structure and unclear flake shape.

The method for preparing ZnO with a hierarchical structure by regulating the chiral molecules disclosed in the embodiment of the present invention comprises the following steps: adding zinc acetate dihydrate and ammonium carbonate to a chiral molecule solution to generate a precipitation reaction, then synthesizing the precipitate in the chiral molecule solution into crystals by a hydrothermal method, and finally calcining the crystals to obtain ZnO with a hierarchical structure. The chiral molecules induce the crystal face to grow in a certain direction to obtain a sheet-like nanostructure; the induction of the chiral molecules forces the obtained sheet-like nanostructure to curl along a certain axial direction, generating a fine deformation axis, and obtaining a nanoflower structure with a curled spiral shape; by changing the polarity of the solvent, the deprotonation degree of the chiral molecules is changed, and the interaction between the chiral molecules and Zn2 ⁺ or the crystal face is indirectly improved, and a nanoflower structure with different curled spiral shapes is prepared; the ZnO with the spiral nanoflower structure has a complex hierarchical structure, a large specific surface area, and can generate more active catalytic center sites, thereby improving the catalytic performance of ZnO.

The method for preparing ZnO with a hierarchical structure by regulating chiral molecules disclosed in the embodiment of the present invention is simple and efficient, has high energy utilization rate, good repeatability and high controllability.

The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the present invention. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.

Claims (10)

1. A method for preparing ZnO having a hierarchical structure by regulating a chiral molecule, characterized in that it comprises: S1. Prepare a chiral molecular solution; S2, adding zinc acetate dihydrate to the two-handed molecular solution and stirring evenly to obtain a mixed solution; S3, adding ammonium carbonate to the mixed solution and stirring for a certain period of time; S4, placing the mixed solution obtained in step S3 in a polytetrafluoroethylene-lined autoclave for hydrothermal reaction; S5. Centrifugally separate the reaction product obtained in step S4, and then calcine it to obtain ZnO with a hierarchical structure. 2. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 1, characterized in that the step S1 specifically comprises: The two-handed molecule is added into ultrapure water, a mixed solution of DMF and ultrapure water, a mixed solution of ethanol and ultrapure water, or a mixed solution of ethylene glycol and ultrapure water, and stirred until dissolved to obtain a two-handed molecule solution. 3. The method for preparing ZnO with a hierarchical structure by regulating the chiral molecules according to claim 1 or 2, characterized in that the chiral molecules include methionine and cysteine. 4. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 3, characterized in that the methionine is L-methionine, and the cysteine is L-cysteine. 5. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 2, characterized in that the volume ratio of the ultrapure water to the DMF is 1:1. 6 . The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 2 , wherein the volume ratio of the ultrapure water to the ethanol is 1:1. 7. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 2, characterized in that the volume ratio of the ultrapure water to the ethylene glycol is 1:1. 8. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 1, characterized in that in step S3, the stirring reaction time is 30 minutes. 9. The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 1, characterized in that the reaction temperature of the hydrothermal reaction is 120°C and the reaction time is 2 hours. 10 . The method for preparing ZnO with a hierarchical structure by regulating chiral molecules according to claim 1 , wherein the calcination temperature is 550° C. and the calcination time is 6 hours.