Copper sulfide triangular nanosheets and methods of making the same

Abstract

This invention discloses copper sulfide triangular nanosheets and their preparation method, relating to the field of nanomaterials technology. The specific preparation method is as follows: a copper source is dispersed in oleylamine to obtain mixture A; sulfur powder is dispersed in oleylamine to obtain mixture B; mixture B is injected into mixture A, and the mixture is kept at 70-100℃ for 3-6 hours. After washing, copper sulfide triangular nanosheets with controllable thickness are obtained. The preparation process of this invention has low raw material costs, good process controllability, high controllability of product morphology, uniform size distribution, and excellent quality, which is beneficial for the mass production and industrialization of copper sulfide triangular nanosheets.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to copper sulfide triangular nanosheets and their preparation methods. Background Technology

[0002] In the field of semiconductor nanomaterials, copper sulfide nanomaterials possess narrow band gaps and strong absorption characteristics in the near-infrared region, attracting widespread research interest in photothermal conversion, thermoelectric conversion, and photothermal therapy. Two-dimensional copper sulfide (CuS) nanomaterials exhibit unique physicochemical properties due to their special structure, often displaying anisotropy. Controllable preparation of two-dimensional copper sulfide semiconductor nanomaterials, achieving precise control over their size and morphology, is key to optimizing their performance.

[0003] In terms of material preparation, two-dimensional copper sulfide nanomaterials prepared by various methods have been reported in recent years, with morphologies mostly concentrated in nanodisc structures, and relatively few reports on triangular sheet structures. This is because hexagonal copper sulfide with an indigotite structure does not possess typical triangular symmetry. Especially at small sizes, high asymmetry leads to higher activity, making the controllable synthesis of copper sulfide triangular nanosheets, particularly thickness control, extremely difficult. Although existing solution-phase synthesis methods can obtain copper sulfide triangular nanosheets, precise thickness control is difficult at small sizes. This is mainly because the solution growth process involves many and complex influencing factors, making it difficult to unify surface ligand control and kinetic growth control. In other words, there are still many difficulties in preparing copper sulfide triangular nanosheets with controllable thickness. A process route for the controllable preparation of copper sulfide triangular nanosheets with controllable thickness urgently needs to be developed. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes copper sulfide triangular nanosheets and their preparation method. The preparation process has low raw material cost, good process controllability, high controllability of product morphology, uniform size distribution, and excellent quality, which is conducive to the mass production and industrialization of copper sulfide triangular nanosheets.

[0005] The present invention proposes a method for preparing copper sulfide triangular nanosheets, the method steps of which are as follows: S1: Disperse the copper source in oleylamine to obtain mixture A; S2: Disperse sulfur powder in oleylamine to obtain mixture B; S3: Inject mixture B into mixture A, keep warm at 70-100℃ for 3-6 hours, and after washing, copper sulfide triangular nanosheets with controllable thickness are obtained.

[0006] Preferably, the copper source is cuprous iodide and / or cuprous chloride.

[0007] Preferably, the mass fraction of copper in mixture A is 0.36%-0.50%.

[0008] Preferably, mixture A is first heated to 110-120°C under an inert atmosphere, held at that temperature for 10-60 minutes, and then cooled to 70-100°C.

[0009] Preferably, the mass fraction of sulfur powder in mixture B is 3.2%-4.4%.

[0010] Preferably, the molar ratio of copper source to sulfur powder is 0.44-0.56:1.

[0011] Preferably, the purity of oleylamine in S1 and S2 is 88%-90%.

[0012] Preferably, the washing method is centrifugation with cyclohexane or ethanol, and the washing is performed no less than three times.

[0013] The present invention proposes a copper sulfide triangular nanosheet, which is prepared by the above-described method.

[0014] Preferably, the copper sulfide triangular nanosheets have an average side length of 40-68 nm, an average thickness of 2.4-4.5 nm, and the number of triangular nanosheets accounts for more than 95%.

[0015] Beneficial technical effects of the present invention: (1) This invention uses a reaction system composed of a copper source, oleylamine, and sulfur powder, and employs a temperature control method of high-temperature pretreatment followed by natural cooling. This allows the copper source to first form a stable and dispersed copper source system in oleylamine, and then undergo a sulfidation reaction with the sulfur source at a lower temperature. This process can slow down the rapid generation and high-temperature ripening of copper sulfide crystal nuclei, allowing copper sulfide nanocrystals to grow anisotropically along specific crystal planes under the joint regulation of the concentrations of oleylamine, iodide ions, and sulfur source, thereby obtaining copper sulfide triangular nanosheets with regular morphology and uniform size distribution.

[0016] (2) In the reaction system of this invention, a higher amount of sulfur powder is not necessarily more conducive to the formation of triangular nanosheets. On the contrary, when the amount of sulfur powder added is too high, the sulfidation reaction rate in the system is too fast, which can easily destroy the directional regulation effect of oleylamine and iodide ions on the growth of copper sulfide crystal faces, resulting in the coexistence of multiple morphologies such as hexagonal nanosheets, nanoparticles and triangular nanosheets in the product, leading to a decrease in the proportion of triangular nanosheets. This invention controls a lower proportion of sulfur powder added to match the sulfidation reaction rate, crystal face growth rate and ligand adsorption regulation effect, thereby obtaining copper sulfide triangular nanosheets with a triangular nanosheet proportion of more than 95%.

[0017] (3) In the reaction system of the present invention, a higher reaction temperature is not necessarily more conducive to the formation of copper sulfide triangular nanosheets. On the contrary, when mixture B is injected into mixture A and the reaction continues at a high temperature of 120°C, the copper sulfide nanocrystals are prone to further ripening and transformation into more stable morphologies such as hexagons, making it difficult to maintain the triangular morphology. The present invention pre-treats the mixture of copper source and oleylamine at high temperature, then naturally cools it to 70-100°C before introducing the sulfur source and holding the reaction at that temperature. This allows the copper sulfide nanocrystals to grow in a controlled manner at a lower temperature, avoiding excessive ripening and morphological transformation under high temperature conditions, thereby achieving the stable preparation of high-purity triangular nanosheets.

[0018] (4) This invention achieves both high morphological purity and adjustable thickness in the obtained copper sulfide triangular nanosheets through the synergistic control of a low sulfur powder addition ratio and a low-temperature reaction window. The results of the examples show that this invention can obtain copper sulfide triangular nanosheets with an average side length of 40-68 nm, an average thickness of 2.5-4.5 nm, and a triangular nanosheet content greater than 95%. Furthermore, by adjusting the reaction temperature and reaction conditions, the side length and thickness of the triangular nanosheets can be controlled within a certain range, which is beneficial for meeting the requirements of different optical, electrical, and photothermal conversion application scenarios regarding nanosheet size and thickness.

[0019] (5) The preparation method of the present invention uses cuprous iodide, sulfur powder and oleylamine as the main raw materials. It does not require complex templates, seed crystals or multi-step post-processing. The reaction steps are simple, the reaction conditions are mild, and the product can be obtained by conventional centrifugation and washing. This method has the advantages of readily available raw materials, controllable process, good repeatability and uniform product size distribution. It is beneficial to the scale-up preparation of copper sulfide triangular nanosheet materials and their application in near-infrared absorbing materials, photothermal conversion materials and electrical functional materials. Attached Figure Description

[0020] Figure 1 The X-ray diffraction (XRD) pattern of copper sulfide triangular nanosheets prepared in Example 1 of this invention is shown.

[0021] Figure 2 This is a transmission electron microscope (TEM) image of the copper sulfide triangular nanosheets prepared in Example 1 of the present invention.

[0022] Figure 3 The UV-Vis-NIR absorption spectrum of copper sulfide triangular nanosheets prepared in Example 1 of this invention is shown.

[0023] Figure 4 The X-ray diffraction (XRD) pattern of copper sulfide triangular nanosheets prepared in Example 2 of this invention is shown.

[0024] Figure 5This is a transmission electron microscope (TEM) image of the copper sulfide triangular nanosheets prepared in Example 2 of this invention.

[0025] Figure 6 The ultraviolet-visible-near-infrared (UV-Vis-NIR) absorption spectrum of copper sulfide triangular nanosheets prepared in Example 2 of this invention is shown.

[0026] Figure 7 This is a transmission electron microscope (TEM) image of the copper sulfide nanomaterials prepared in Comparative Example 1 of this invention.

[0027] Figure 8 This is a transmission electron microscope (TEM) image of the copper sulfide nanomaterials prepared in Comparative Example 2 of this invention. Detailed Implementation

[0028] The present invention will be further explained below with reference to specific embodiments.

[0029] Example 1 In a 50 mL round-bottom flask, add 0.19 g of cuprous iodide and 18 mL of oleylamine, mix and stir until homogeneous to obtain mixed solution A; place the above solution A in an oil bath at 120 °C for 20 min, then allow it to cool naturally to 100 °C; add 0.06 g of sulfur powder to 2 mL of oleylamine solvent, and stir ultrasonically until homogeneous to obtain mixed solution B; pour the above solution B into solution A and keep it at 100 °C for 6 h; wash three times or more by centrifugation with cyclohexane or ethanol, collect the precipitate, and the copper sulfide triangular nanosheet material can be obtained.

[0030] Depend on Figure 1 As can be seen, the characteristic diffraction peaks of the XRD pattern of the product obtained in this embodiment indicate that the product is mainly composed of hexagonal copper sulfide (CuS), and the peak positions of the diffraction peaks are in good agreement with the standard card.

[0031] Depend on Figure 2 As can be seen from the TEM image of the copper sulfide nanomaterial in this embodiment, the morphology of the product is triangular nanosheets. The product has a uniform size distribution, with an average side length of 65.6±10.2 nm and an average thickness of 4.4±0.3 nm. The purity of the triangular nanosheets is >95%, indicating that the process of this invention has good controllability.

[0032] Depend on Figure 3 As can be seen, the UV-Vis-NIR results show that the product has a large absorption peak in the 750-1100 nm range, indicating that it exhibits excellent light absorption characteristics in the near-infrared region.

[0033] Example 2 In a 50 mL round-bottom flask, add 0.38 g of cuprous iodide and 35 mL of oleylamine, mix and stir until homogeneous to obtain mixed solution A; place the above solution A in an oil bath at 115 °C for 30 min, then allow it to cool naturally to 80 °C; add 0.13 g of sulfur powder to 4 mL of oleylamine solvent, and stir ultrasonically until homogeneous to obtain mixed solution B; pour the above solution B into solution A and continue to keep it at 80 °C for 6 h; wash three times or more with cyclohexane or ethanol, collect the precipitate, and the copper sulfide triangular nanosheet material can be obtained.

[0034] Depend on Figure 4 As can be seen, the characteristic diffraction peaks of the XRD pattern of the product obtained in this embodiment indicate that the product is mainly composed of hexagonal copper sulfide (CuS), and the peak positions of the diffraction peaks are in good agreement with the standard card.

[0035] Depend on Figure 5 As can be seen from the TEM image of the copper sulfide nanomaterial in this embodiment, the morphology of the product is triangular nanosheets. The product has a uniform size distribution, with an average side length of 47.6±6.1 nm and an average thickness of 2.9±0.4 nm. The purity of the triangular nanosheets is >95%, indicating that the process of this invention has good controllability.

[0036] Depend on Figure 6 As can be seen, the UV-Vis-NIR results show that the product has a large absorption peak in the 750-1100 nm range, indicating that it exhibits excellent light absorption characteristics in the near-infrared region.

[0037] Comparative Example 1 In a 50 mL round-bottom flask, add 0.38 g of cuprous iodide and 35 mL of oleylamine, mix and stir until homogeneous to obtain mixed solution A; place the above solution A in an oil bath at 120 °C for 30 min; add 0.13 g of sulfur powder to 4 mL of oleylamine solvent, and stir ultrasonically until homogeneous to obtain mixed solution B; pour the above solution B into solution A and continue to keep it at 120 °C for 6 h; wash three times or more by centrifugation with cyclohexane or ethanol, collect the precipitate, and the copper sulfide triangular nanosheet material can be obtained.

[0038] Depend on Figure 7 As can be seen, the morphology of the product obtained in this comparative example is as follows: Figure 7 As shown, the copper sulfide has a hexagonal morphology, indicating that this method cannot be used to prepare triangular nanosheets at high temperatures.

[0039] Comparative Example 2 In a 50 mL round-bottom flask, add 0.19 g of cuprous iodide and 18 mL of oleylamine, mix and stir until homogeneous to obtain mixed solution A; place the above solution A in an oil bath at 115 °C for 30 min, then allow it to cool naturally to 100 °C; add 0.06 g of sulfur powder to 2 mL of oleylamine solvent, and stir ultrasonically until homogeneous to obtain mixed solution B; pour the above solution B into solution A and continue to keep it at 100 °C for 6 h; wash three times or more by centrifugation with cyclohexane or ethanol, collect the precipitate, and the copper sulfide triangular nanosheet material can be obtained.

[0040] Depend on Figure 8 As can be seen, the morphology of the product obtained in this comparative example is as follows: Figure 8 As shown, the morphology of the copper sulfide is a mixture of hexagonal nanosheets, nanoparticles and triangular nanosheets, indicating that it is difficult to obtain high-purity copper sulfide triangular nanosheets using this method at high sulfur content ratios.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents, all of which should be included within the scope of protection of the invention.

Claims

1. A method for preparing copper sulfide triangular nanosheets, characterized in that, The steps are as follows: S1: Disperse the copper source in oleylamine to obtain mixture A; S2: Disperse sulfur powder in oleylamine to obtain mixture B; S3: Inject mixture B into mixture A, keep warm at 70-100℃ for 3-6 hours, and after washing, copper sulfide triangular nanosheets with controllable thickness are obtained.

2. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The copper source is cuprous iodide and / or cuprous chloride.

3. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The mass fraction of copper in mixture A is 0.36%-0.50%.

4. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, Mixture A is first heated to 110-120℃ under an inert atmosphere and held for 10-60 minutes, and then cooled to 70-100℃.

5. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The mass fraction of sulfur powder in mixture B is 3.2%-4.4%.

6. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The molar ratio of copper source to sulfur powder is 0.44-0.56:

1.

7. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The purity of oleylamine in S1 and S2 is 88%-90%.

8. The method for preparing copper sulfide triangular nanosheets according to claim 1, characterized in that, The washing method involves centrifuging with cyclohexane or ethanol, and the washing process should be repeated at least three times.

9. A copper sulfide triangular nanosheet, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The copper sulfide triangular nanosheet according to claim 9, characterized in that, The copper sulfide triangular nanosheets have an average side length of 40-68 nm, an average thickness of 2.4-4.5 nm, and the number of triangular nanosheets accounts for more than 95%.

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