Preparation method of nano-zinc sulfide composite material

Abstract

This invention discloses a method for preparing a nano-zinc sulfide composite material, comprising: (1) dissolving ammonium molybdate in deionized water, stirring evenly to form a 50 g / L solution, then sequentially adding zinc acetate and thiourea, wherein the mass ratio of ammonium molybdate to zinc acetate and thiourea is 2:1, and stirring thoroughly to obtain a mixed solution; (2) transferring the obtained mixed solution to a reaction vessel, reacting at a constant temperature of 160℃ for 12 h, and obtaining a solid powder after treatment; (3) heat-treating at 300-400℃ for 2 h to obtain the nano-zinc sulfide composite material. This invention synthesizes zinc sulfide nanomaterials with different sizes and morphologies, while molybdenum dioxide nanoparticles modify the surface of zinc sulfide. The two work synergistically to have heterogeneous structural characteristics that promote and accelerate electron transport. Using them as electrode materials for electrochemical detection of nicotine and the metabolite cotinine content in cigarettes shows potential application advantages.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically to a method for preparing a nano-zinc sulfide composite material. Background Technology

[0002] Zinc sulfide is considered one of the most widely used materials due to its excellent physicochemical properties, low cost, high stability, and wide bandgap. The diverse nanostructures of zinc sulfide make it a potential candidate for applications such as photocatalysts, sensing materials, organic-inorganic field-effect transistors, and optical modulators. To further improve material properties, composite formation, doping, and morphological manipulation are effective methods for achieving performance optimization. Existing literature reports methods for composite or doped zinc sulfide materials including physical vapor deposition [Vacuum, 2016, 130, 154], chemical vapor deposition [J. Phys. Chem. B 2000, 104, 1150], electrochemical deposition [J. Electroanal. Chem. 2017, 794, 212–220], chemical precipitation [Appl. Phy. A 2023, 129, 346], and chemical bath deposition [Mater. Sci. Semicond. Proc. 2021, 130, 105825]. Some of these methods are complex or costly. Synthesizing nano-zinc sulfide composite multifunctional materials with controllable morphology and structure using simple methods remains a technical challenge.

[0003] Nicotine is a pyridine alkaloid commonly found in tobacco. Medical research has shown that nicotine has a significant impact on the nervous system, potentially leading to lung cancer and neurological disorders. Furthermore, nicotine's metabolite is cotinine. Therefore, accurate detection of nicotine and cotinine is crucial. Currently, detection methods rely on instruments such as gas chromatography, liquid chromatography, chromatography / mass spectrometry, high-performance liquid chromatography, and fluorescence spectroscopy. These methods require specialized equipment and are relatively expensive. In contrast, electrochemical analysis methods offer advantages such as simplicity, rapid response, high sensitivity, and portability, making them a promising analytical approach. Therefore, effective electrode materials are key to electrochemical detection technology. Summary of the Invention

[0004] To address the problems of existing technologies, the purpose of this invention is to design and prepare a nano-zinc sulfide composite material for the electrochemical detection of different concentrations of nicotine and cotinine.

[0005] This invention is achieved using the following technical solution:

[0006] A method for preparing a nano-zinc sulfide composite material includes the following steps:

[0007] (1) Dissolve ammonium molybdate in deionized water to form a solution with a mass concentration of 50 g / L. Then add zinc acetate and thiourea in sequence. The mass ratio of ammonium molybdate to (zinc acetate and thiourea) is 2:1. Stir thoroughly to obtain a mixed solution.

[0008] (2) The obtained mixed solution is transferred to a reaction vessel and reacted at a constant temperature of 150℃~180℃. After processing, a solid powder is obtained.

[0009] (3) The obtained solid is heat-treated at 300-400℃ to obtain nano zinc sulfide composite material.

[0010] This invention selects appropriate hydrothermal conditions to promote the nucleation and growth of zinc ions and sulfur source at the molecular level. Molybdate ions are adsorbed onto the nucleus surface through electrostatic interaction. The resulting solid is then heat-treated to generate molybdenum dioxide nanoparticles that adhere to the surface of a two-dimensional zinc sulfide sheet, thus achieving an effective composite of zero-dimensional and two-dimensional materials.

[0011] More preferably, in step (1), the molar ratio of zinc acetate to thiourea is 1:1.

[0012] In a further preferred embodiment, in step (2), the reaction is carried out at a constant temperature of 160℃ for 12 hours.

[0013] In a further preferred embodiment, in step (3), the heat treatment is carried out at 350°C for 2 hours.

[0014] The key technical aspects of this invention are mainly reflected in the following aspects:

[0015] 1. This invention precisely controls the morphology and structure of nano-zinc sulfide composite materials. To address the problem of nano-zinc sulfide composite materials being composed of zero-dimensional and two-dimensional materials, this application, through multiple experiments, obtained the necessary preparation process parameters.

[0016] 2. The present invention determined through experiments that the mass concentration of ammonium molybdate solution is 50 g / L. Under the condition that the mass ratio of ammonium molybdate to (zinc acetate and thiourea) is 2:1, the concentration of ammonium molybdate solution was changed to 40 g / L and 60 g / L respectively. At higher concentrations, molybdenum and zinc ions are not well dispersed, and the size of zinc sulfide is difficult to control, affecting performance. At lower concentrations (e.g., in Example 1 and...), the concentration of ammonium molybdate solution is... Figure 2 The larger particle size of zinc sulfide also affects its performance.

[0017] 3. In step (2) of the present invention, if the temperature of the hydrothermal reaction is too high and the time is too long, it is easy to form larger particles and blocks, and the crystallinity will also increase, resulting in a reduction of active sites.

[0018] 4. Through experiments, this invention determined that the optimal heat treatment temperature in step (3) is 350℃. If the heat treatment temperature is too high or too low, the product will become densely stacked, affecting its performance. If the heat treatment time is too long, it will easily lead to the sintering of nanoparticles and nanosheets, affecting their activity.

[0019] 5. The heterogeneous structure of the nano-zinc sulfide composite material of the present invention can accelerate electron transport. Since there are nitrogen electron pairs in nicotine and cotinine molecules, the nano-zinc sulfide composite material has the ability to accelerate electron transport, promote electron transfer and oxidize the molecules, and realize the detection of nicotine and cotinine.

[0020] This invention features a well-designed and synthesized nano-zinc sulfide composite material with controllable size and morphology. The nanoparticles and two-dimensional nanosheets synergistically promote and accelerate electron transport. When used as an electrode material for the electrochemical detection of nicotine and cotinine metabolites in cigarettes, the results show that the prepared zinc sulfide composite material has dual-functionality, capable of detecting both different concentrations of nicotine and different concentrations of cotinine metabolites. This dual-functionality exhibited by the nano-zinc sulfide composite material has significant practical application value. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The XRD patterns of the nano-zinc sulfide composite materials prepared in Examples 1 to 3 are shown.

[0024] Figure 2 The image shows a scanning electron microscope (SEM) image of the nano-zinc sulfide composite material prepared in Example 1.

[0025] Figure 3 The image shows a scanning electron microscope (SEM) image of the nano-zinc sulfide composite material prepared in Example 2.

[0026] Figure 4 The image shows a scanning electron microscope (SEM) image of the nano-zinc sulfide composite material prepared in Example 3. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0028] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0030] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Example 1

[0031] A method for preparing a nano-zinc sulfide composite material includes the following steps:

[0032] 1. Dissolve 2g of ammonium molybdate ((NH4)2MoO4, 0.01mol) in 50mL of deionized water and stir until a solution of 40g / L is formed. Then add 0.7g of zinc acetate ((CH3COO)2Zn, 0.004mol) and 0.3g of thiourea (CH4N2S, 0.004mol) and stir to form a mixed solution. The mass ratio of ammonium molybdate to (zinc acetate and thiourea) is 2:1, and the molar ratio of zinc acetate to thiourea is 1:1.

[0033] 2. The obtained mixed solution was transferred to a reaction vessel and reacted at a constant temperature of 160℃ for 12 hours. After centrifugation, washing and drying, a solid powder was obtained.

[0034] 3. The obtained solid was subjected to constant temperature treatment at 300℃ for 2 hours to obtain nano zinc sulfide composite material.

[0035] The XRD characterization results of the composite material prepared in Example 1 are shown in the appendix. Figure 1 The characteristic diffraction peaks shown in the figure indicate that the synthesized material possesses the characteristic crystal structure of zinc sulfide. Electron microscopy characterization images are attached. Figure 2Electron microscopy images show that the synthesized material consists of stacked hexagonal nanoblocks of zinc sulfide and surface-adhered molybdenum dioxide nanoparticles.

[0036] A certain amount of the nanocomposite material prepared in Example 1 was weighed and made into a 10 g / L ethanol dispersion. Two microliters of the dispersion were then added dropwise to the electrode surface to form a working electrode. This electrode was placed in a three-electrode system, and nicotine and cotinine were detected using an electrochemical testing method. The test results are shown in Table 1. The results indicate that the electrode exhibits high sensitivity in detecting nicotine and cotinine within a certain concentration range, with response values ​​reaching 0.6–0.9 μA and 0.29–0.39 μA, respectively. Example 2

[0037] A method for preparing a nano-zinc sulfide composite material includes the following steps:

[0038] 1. Dissolve 2.5g of ammonium molybdate ((NH4)2MoO4, 0.013mol) in 50mL of deionized water and stir until a 50g / L solution is formed. Then add 0.86g of zinc acetate ((CH3COO)2Zn, 0.005mol) and 0.35g of thiourea (CH4N2S, 0.005mol) and stir to form a mixed solution. The mass ratio of ammonium molybdate to (zinc acetate and thiourea) is 2:1 (i.e., 2.5 / 1.21≈2), and the molar ratio of zinc acetate to thiourea is 1:1.

[0039] 2. The obtained mixed solution was transferred to a reaction vessel and reacted at a constant temperature of 160℃ for 12 hours. After centrifugation, washing and drying, a solid powder was obtained.

[0040] 3. The obtained solid was subjected to constant temperature treatment at 350℃ for 2 hours to obtain nano zinc sulfide composite material.

[0041] The XRD characterization results of the composite material prepared in Example 2 are attached. Figure 1 The characteristic diffraction peaks shown in the figure indicate that the synthesized material possesses the characteristic crystal structure of zinc sulfide. Electron microscopy characterization images are attached. Figure 3 Electron microscopy images show that the synthesized composite material consists of zinc sulfide layers of square nanosheets and molybdenum dioxide nanoparticles adhered to the surface.

[0042] A certain amount of the nanocomposite material prepared in Example 2 was weighed and made into a 10 g / L ethanol dispersion. 2 μL of the dispersion was added dropwise to the electrode surface to form a working electrode. The electrode was placed in a three-electrode system and nicotine and cotinine were detected using an electrochemical testing method. The test results are shown in Table 1. The results show that the detection of nicotine and cotinine exhibits significant high sensitivity over a wide concentration range, with response values ​​reaching 2.4–4.4 μA and 1.4–1.7 μA, respectively. Example 3

[0043] A method for preparing a nano-zinc sulfide composite material includes the following steps:

[0044] 1. Dissolve 2.5g of ammonium molybdate in 50mL of deionized water and stir until a solution with a mass concentration of 50g / L is formed. Then add 0.86g of zinc acetate and 0.35g of thiourea and stir to form a mixed solution.

[0045] 2. The obtained mixed solution was transferred to a reaction vessel and reacted at a constant temperature of 160℃ for 12 hours. After centrifugation, washing and drying, a solid powder was obtained.

[0046] 3. The obtained solid was subjected to constant temperature treatment at 400℃ for 2 hours to obtain nano zinc sulfide composite material.

[0047] The XRD characterization results of the composite material prepared in Example 3 are attached. Figure 1 The characteristic diffraction peaks shown in the figure indicate that the synthesized material has the characteristic crystal structure of zinc sulfide; electron microscopy characterization images are attached. Figure 4 Electron microscopy images show that the synthesized composite material consists of zinc sulfide layers of square nanosheets and molybdenum dioxide nanoparticles adhered to the surface.

[0048] A certain amount of the nanosheet material prepared in Example 3 was weighed and made into a 10 g / L ethanol dispersion. 2 μL of the dispersion was added to the electrode surface to form a working electrode. The electrode was placed in a three-electrode system and nicotine and cotinine were detected by electrochemical testing. The test results are shown in Table 1. The results show that the detection of nicotine and cotinine showed high sensitivity over a wide concentration range, with response values ​​of 1.4–1.8 μA and 1.4–2.1 μA, respectively.

[0049] Table 1. Electrochemical properties of the nano-zinc sulfide composite materials prepared in Examples 1 to 3

[0050]

[0051] The nanocomposites prepared by the technical solutions in the above three embodiments have the same zinc sulfide crystal structure but different microstructures. Optimizing the concentration of ammonium molybdate solution and the heat treatment temperature can control the microstructure and structure of the material. The zinc sulfide nanocomposites prepared in Example 2 have regularly stacked square nanosheets and uniformly sized nanoparticles, and are considered the optimal embodiment. The materials prepared in all three embodiments can be used for the electrochemical detection of nicotine and cotinine. The materials synthesized in Examples 2 and 3 show large current responses to nicotine and cotinine, respectively, indicating significant application effects. However, the low concentration of ammonium molybdate in Example 1 resulted in a larger zinc sulfide size, which could not effectively utilize the performance of the composite material.

[0052] The method described in this invention is simple to operate and the process conditions are easy to control. It yields a zinc sulfide composite material composed of molybdenum dioxide nanoparticles and two-dimensional zinc sulfide ordered nanosheets, thus synthesizing zinc sulfide nanomaterials with different sizes and morphologies. At the same time, the molybdenum dioxide nanoparticles modify the surface of the zinc sulfide. The two work together to have the heterogeneous structure characteristics of promoting and accelerating electron transport. Using it as an electrode material for the electrochemical detection of nicotine and the metabolite cotinine in cigarettes shows potential application advantages.

[0053] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A method for preparing a nano-zinc sulfide composite material, wherein the nano-zinc sulfide composite material is used for electrochemical detection of different concentrations of nicotine and cotinine, characterized in that: Includes the following steps: (1) Dissolve ammonium molybdate in deionized water to form a solution with a mass concentration of 50 g / L. Then add zinc acetate and thiourea in sequence. The mass ratio of ammonium molybdate to zinc acetate and thiourea is 2:

1. Stir thoroughly to obtain a mixed solution. (2) The obtained mixed solution was transferred to a reaction vessel and reacted at a constant temperature of 160℃ for 12 hours. After processing, a solid powder was obtained. (3) Heat treatment at 350-400℃ for 2 hours to obtain nano zinc sulfide composite material, which is composed of zinc sulfide stacked on square nanosheets and molybdenum dioxide nanoparticles adhered to the surface.

2. The method for preparing a nano-zinc sulfide composite material according to claim 1, characterized in that: In step (1), the molar ratio of zinc acetate to thiourea is 1:1.

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