A method for preparing zinc nanosheets and zinc nanosheets prepared thereby
By combining thermal reduction with the use of organic amines, single-crystal zinc nanosheets with adjustable size were successfully prepared, solving the problems of high energy consumption, low yield and unstable morphology in the existing technology. This method achieves the preparation of zinc nanosheets with high yield and large aspect ratio, which is suitable for optical, electrical and energy fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WESTLAKE UNIV
- Filing Date
- 2026-04-22
- Publication Date
- 2026-05-29
AI Technical Summary
Existing methods for preparing zinc nanosheets are energy-intensive, have low yields, and are difficult to control in terms of morphology. Furthermore, nanosheets are easily oxidized or broken during liquid-phase synthesis. Existing liquid-phase reduction methods can only prepare zinc nanosheets with limited size and thickness.
A thermal reduction method was used to prepare single-crystal zinc nanosheets with adjustable size and a thickness of less than 10 nm by mixing zinc precursor with organic amine in a solvent and controlling the reaction temperature and the type of organic amine. Hexagonal nanosheet structures were obtained by using organic amine as a reducing agent and morphology control agent.
A highly efficient and simple method was developed to prepare single-crystal zinc nanosheets with a large aspect ratio, with a yield of up to 25%. The nanosheets are mechanically flexible and can be used to assemble macroscopic structures such as nanosheet films.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterials, specifically relating to a method for preparing zinc nanosheets and the ultrathin single-crystal zinc nanosheets prepared therefrom. Background Technology
[0002] Metal nanomaterials possess both the inherent high electrical and thermal conductivity of metals and the unique physicochemical properties conferred by the nanoscale, such as high catalytic activity and localized surface plasmon resonance effects. They have been increasingly applied in optics, electronics, and energy, thus holding significant research value in numerous fields. Two-dimensional metal nanosheets, with their high aspect ratio and unique surface effects, have attracted the attention of researchers in condensed matter physics, chemistry, and materials science, becoming a hot topic in nanomaterials research in recent years.
[0003] In recent years, active zinc nanomaterials have attracted widespread attention in energy storage, catalysis, and corrosion protection due to their low cost, high reactivity, and unique ultraviolet photonic properties. Existing methods for preparing zinc nanosheets include vapor deposition, electrochemical template methods, and liquid-phase synthesis. Vapor deposition of zinc nanosheets is energy-intensive, has low yield, and its morphology is difficult to control, often relying on the use of special substrates (such as single-crystal silicon). Electrochemically deposited zinc nanosheets often clump together, cannot be dispersed, and are severely oxidized. While combining ultrasound during electrochemical deposition can yield well-dispersed nanosheets, it also causes nanosheet breakage, compromising morphology, and ultrasound exacerbates oxidation.
[0004] Currently, there are few reports on the liquid-phase synthesis of active metallic zinc nanosheets. According to the relevant literature available to the inventors, only "Chemical synthesis of blue-emitting metallic zinc nanoohexagons" (Nguyen T. Mai et. al., CrystEngComm, 2013, 15, 6606-6610) was published in 2013. The authors used a liquid-phase reduction strategy, with zinc chloride as a precursor, lithium triisobutylborohydride as a reducing agent, oleylamine as a surfactant, and diphenyl ether as a solvent, to prepare metallic zinc nanosheets at a high temperature of 200℃. The nanosheets had a size of only 200-350 nm and a thickness of 20-40 nm. Summary of the Invention
[0005] The purpose of this invention is to propose a method for synthesizing zinc nanosheets. This method is convenient and simple to operate, and can stably and efficiently prepare hexagonal single-crystal zinc nanosheets. Compared with the existing methods, the liquid-phase synthesis strategy proposed in this invention uses fewer reagents, is simpler to operate, and has milder reaction conditions. Furthermore, the synthesized nanosheets have a larger aspect ratio, with dimensions adjustable from 200 nm to 4 μm and a thickness of less than 10 nm.
[0006] The zinc nanosheets prepared by this invention are synthesized by a thermal reduction method, which can stably and efficiently prepare zinc nanosheets. The zinc nanosheets obtained are single crystal structures with adjustable size in the range of 200 nm to 4 μm and thickness of less than 10 nm.
[0007] According to one aspect of the present invention, a method for preparing zinc nanosheets is provided, comprising the following steps: (1) A zinc precursor and an organic amine are mixed in a solvent to obtain a mixture; (2) The mixture is heated so that the organic amine reduces the zinc precursor to obtain zinc nanosheets; The zinc precursor is ZnR1R2, wherein R1 and R2 are independently selected from alkyl groups having 2-10 carbon atoms, i.e., C2-C10 alkyl groups, preferably C2-C6 alkyl groups, and more preferably C2-C4 alkyl groups; the organic amine is selected from one or more combinations of oleylamine and alkylamine, wherein the alkylamine is C n H 2n+1 NH2, where n is an even number between 8 and 26, preferably an even number between 8 and 22.
[0008] In some embodiments, R1 and R2 are the same as each other. In particular, the zinc precursor includes, but is not limited to, diethylzinc, dipropylzinc, diisobutylzinc, etc.
[0009] Zinc nanosheets can be successfully obtained using the zinc precursor described above.
[0010] Furthermore, the organic amine used in the synthesis acts as both a reducing agent and a surfactant to control the morphology, reducing the zinc precursor to metallic zinc with a hexagonal nanosheet structure.
[0011] In some embodiments, the organic amine includes oleylamine, octadecylamine, hexadecylamine, tetradecylamine, dodecylamine, decylamine, and octylamine.
[0012] Using the above-mentioned surfactants is beneficial for obtaining zinc nanosheets with uniform morphology and controllable size. However, without the above-mentioned organic amines, such as pentadecylamine containing an odd number of carbon atoms or hexylamine with less than 8 carbon atoms, only trace amounts of metallic zinc products can be obtained, and the products have irregular morphology.
[0013] In some embodiments, in step (1), the solvent is one or more selected from n-hexane, cyclohexane, pentane, toluene, tetrahydrofuran, and 1,4-dioxane.
[0014] In some embodiments, the concentration of the zinc precursor is 0.5-2 mol / L, such as 0.5, 0.8, 1.0, 1.5, 2.0 mol / L, etc., in terms of the molar concentration of zinc. Within the above range, zinc nanosheets with uniform size can be obtained, while excessively high concentrations may result in irregular zinc nanosheet morphologies.
[0015] In some embodiments, the amount of organic amine used is 1.2-1.8 times that of the zinc precursor, in terms of the molar concentration of zinc. Within this range, zinc nanosheets with uniform size can be obtained; however, if the concentration is too low, irregular zinc nanosheet morphology may result.
[0016] In some embodiments, the reaction temperature in step (2) can be 130-170°C, such as 130, 140, 150, 160, 170°C, etc. Within the above temperature range, zinc nanosheets with uniform morphology can be obtained. If the temperature is too high, zinc nanosheets with irregular morphology will be produced; while if the temperature is too low, the reaction yield will be reduced.
[0017] Furthermore, in step (2), there is no particular limitation on the reaction time, as long as zinc nanosheets can be obtained. For example, the reaction time can be more than 1 hour or more than 4 hours. According to the morphology of the product, the preferred reaction time is 4 hours. If the reaction time exceeds 6 hours, the proportion of irregular morphology may also increase.
[0018] The method for preparing zinc nanosheets according to the present invention may further include conventional purification steps, in which the reaction product is filtered to obtain a precipitate, which is then washed and dried.
[0019] Washing can be carried out using organic solvents. There are no special requirements for the washing solvent, as long as it can remove the remaining zinc precursor and organic amines. For example, the washing solvent can be one or a combination of two or more of hexane, toluene, tetrahydrofuran, 1,4-dioxane, and isopropanol.
[0020] Drying can be carried out in air, and the evaporation of residual solvent can be accelerated by reducing pressure.
[0021] According to another aspect of the present invention, a zinc nanosheet is provided, which is prepared by the above-described method for preparing zinc nanosheets according to the present invention.
[0022] Furthermore, the zinc nanosheets according to the present invention have a single-crystal structure. In particular, the size of the nanosheets is between 200 nm and 4 μm, and the thickness of the nanosheets is less than 10 nm, for example, 7 nm, 9 nm, etc.
[0023] Beneficial effects Compared with existing methods for preparing zinc nanosheets, the solution synthesis method described in this invention uses simple raw materials, is easy to operate, and allows for adjustable nanosheet size. Furthermore, the synthesized zinc nanosheets are ultrathin (<10 nm) with an aspect ratio reaching 400. This high aspect ratio endows the nanosheets with a certain degree of mechanical flexibility, making them suitable for assembling macroscopic structures such as nanosheet films. The synthesized nanosheets are also single-crystal structures with a yield of up to 25%. Attached Figure Description
[0024] Figure 1 This is a SEM image of the zinc nanosheets synthesized in Example 1.
[0025] Figure 2 The image shows the XRD pattern of zinc nanosheets synthesized in Example 1.
[0026] Figure 3 The image shows a TEM selected area electron diffraction pattern of the zinc nanosheets synthesized in Example 1, proving that the zinc nanosheets are single-crystal structures.
[0027] Figure 4 The image shows a transmission electron microscopy (TEM) image of the cross-section of the zinc nanosheets synthesized in Example 1, demonstrating that the thickness of the zinc nanosheets is less than 10 nm and that the nanosheets have a zinc-zinc oxide core-shell structure.
[0028] Figure 5 For comparison of SEM images of zinc nanosheets synthesized using different organic amines in the examples and comparative examples, (A) octadecylamine; (B) pentadecylamine; (C) dodecylamine; (D) decylamine; (E) octylamine; (F) hexylamine. Detailed Implementation
[0029] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0030] SEM results were obtained using a scanning electron microscope (Themo Scientific).
[0031] The X-ray diffraction results were obtained using a polycrystalline X-ray diffractometer (Bruker).
[0032] TEM results were obtained using a transmission electron microscope (Talos F200X G2).
[0033] Example 1 (1) Add 2 ml of diethylzinc in n-hexane (1 mol / L) as a zinc precursor solution to the reaction vessel; (2) Add 2.4 ml of oleylamine (2.9-3.3 mmol, purity: 80-90%) to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed with hexane, tetrahydrofuran and isopropanol in sequence, and dried under reduced pressure to obtain zinc nanosheets with a yield of about 15%.
[0034] Figure 1 The image shown is a SEM image of the zinc nanosheets synthesized in Example 1; the top right image is a sample photograph. Figure 1 As shown, the synthesized zinc nanosheets have a size of approximately 2-4 μm.
[0035] The results of polycrystalline X-ray diffraction are shown below. Figure 2 Compared with the zinc standard PDF card (PDF 65-3358), the synthesized product is a metallic zinc nanosheet, which only undergoes slight oxidation.
[0036] Selected area electron diffraction results of synthesized zinc nanosheets are as follows: Figure 3 As shown, the synthesized zinc nanosheets have a single crystal structure and the upper surface is a (0002) crystal plane.
[0037] The cross-section of zinc nanosheets is as follows Figure 4 As shown, the nanosheets exhibit a zinc-zinc oxide core-shell structure, with an oxide layer thickness of approximately 1.4 nm, a metallic zinc thickness of approximately 4 nm, and an overall nanosheet thickness of less than 10 nm.
[0038] Example 2 (1) Add 2 ml of diethylzinc in toluene solution (2 mol / L) as zinc precursor solution to the reaction vessel; (2) Add 6 mmol of octadecylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain zinc nanosheets. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 The yield is approximately 25%.
[0039] SEM images of the product are as follows Figure 5 As shown in A.
[0040] Example 3 (1) Add 2 ml of diethylzinc in toluene solution (1 mol / L) as zinc precursor solution to the reaction vessel; (2) Add 3 mmol of hexadecylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain zinc nanosheets. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 The yield is approximately 15%.
[0041] Example 4 (1) Add 2 ml of diethylzinc n-hexane solution (1 mol / L) as the zinc precursor solution into the reaction vessel; (2) Add 3.4 mmol of dodecylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain zinc nanosheets. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 The yield is approximately 15%.
[0042] SEM images of the product are as follows Figure 5 As shown in C.
[0043] Example 5 (1) Add 2 ml of diethylzinc in n-hexane (1 mol / L) as a zinc precursor solution to the reaction vessel; (2) Add 3.4 mmol of decylamine to the above precursor; (3) Mix thoroughly and react at 140℃ for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain zinc nanosheets. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 The yield is approximately 10%.
[0044] SEM images of the product are as follows Figure 5 As shown in D.
[0045] Example 6 (1) Add 2 ml of diethylzinc in toluene solution (1 mol / L) as zinc precursor solution to the reaction vessel; (2) Add 3.6 mmol of octylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 3 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain zinc nanosheets. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2The yield is approximately 8%.
[0046] SEM images of the product are as follows Figure 5 As shown in E.
[0047] The comparative examples use organic amines with an odd number of carbon atoms, such as pentadecylamine; and organic amines with fewer than 8 carbon atoms, such as hexylamine.
[0048] Comparative Example 1 (1) Add 2 ml of diethylzinc in n-hexane (1 mol / L) as a zinc precursor solution to the reaction vessel; (2) Add 2.6 mmol of pentadecylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain irregularly shaped metallic zinc particles. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 .
[0049] SEM images of the product are as follows Figure 5 As shown in B.
[0050] Comparative Example 2 (1) Add 2 ml of diethylzinc in n-hexane (1 mol / L) as a zinc precursor solution to the reaction vessel; (2) Add 3 mmol of hexylamine to the above precursor; (3) Mix thoroughly and react at 150°C for 4 hours; (4) After the reaction was completed, the solid product was washed sequentially with n-hexane, tetrahydrofuran, and isopropanol, and then dried under reduced pressure to obtain irregularly shaped metallic zinc particles. The polycrystalline X-ray diffraction results were basically the same as those obtained by the reaction. Figure 2 .
[0051] SEM images of the product are as follows Figure 5 As shown in F.
[0052] The zinc precursors, organic amines, and process information used in the examples and comparative examples are shown in Table 1.
[0053] Table 1
Claims
1. A method for preparing zinc nanosheets, wherein, The preparation method includes the following steps: (1) A zinc precursor and an organic amine are mixed in a solvent to obtain a mixture; (2) The mixture is heated so that the organic amine reduces the zinc precursor to obtain zinc nanosheets; The zinc precursor is ZnR1R2, wherein R1 and R2 are independently selected from C2-C10 alkyl groups; the organic amine is selected from one or more combinations of oleylamine and alkylamine, wherein the alkylamine is C2-C10 alkyl group. n H 2n+1 NH2, where n is an even number from 8 to 26.
2. The preparation method according to claim 1, wherein, R1 and R2 are independently selected from C2-C6 alkyl groups, and n is an even number of 8-22.
3. The preparation method according to claim 1, wherein, R1 and R2 are independently selected from C2-C4 alkyl groups. For example, the zinc precursor is selected from one or more combinations of diethylzinc, dipropylzinc, and diisobutylzinc; the organic amine is selected from one or more combinations of oleylamine, octadecylamine, hexadecylamine, tetradecylamine, dodecylamine, decylamine, and octylamine.
4. The preparation method according to any one of claims 1 to 3, wherein, In step (1), the solvent is one or more selected from n-hexane, cyclohexane, pentane, toluene, tetrahydrofuran, and 1,4-dioxane.
5. The preparation method according to any one of claims 1 to 4, wherein, The concentration of the zinc precursor is 0.5-2 mol / L, expressed as the molar concentration of zinc.
6. The preparation method according to any one of claims 1 to 5, wherein, The molar ratio of the organic amine to the zinc precursor is 1.2-1.8:
1.
7. The preparation method according to any one of claims 1 to 6, wherein, The reaction temperature for preparing zinc nanosheets in step (2) is 130-170℃; and / or the reaction time is 1-6 hours.
8. The preparation method according to any one of claims 1-7, wherein, The preparation method further includes a purification step: centrifuging the reaction product to obtain a precipitate, and then further washing, centrifuging and drying it.
9. The preparation method according to claim 8, wherein, The washing is performed using an organic solvent, which is one or a combination of two or more of the following: hexanal, toluene, tetrahydrofuran, 1,4-dioxane, and isopropanol.
10. A zinc nanosheet prepared by the preparation method according to any one of claims 1-9; Specifically, the zinc nanosheets are single-crystal structures, and more specifically, the size of the zinc nanosheets is between 200 nm and 4 μm, and the thickness of the nanosheets is less than 10 nm.