A carbon dot-wrapped cuprous oxide nanosheet and a preparation method thereof

Abstract

The application belongs to the field of nanometer material preparation, and particularly relates to carbon dot wrapped cuprous oxide nanoparticles and a preparation method and application thereof. The single-layer carbon dot is used as a special surface wrapping agent due to its unique structure such as an ultrathin structure, a suitable lateral size and abundant oxygen-containing functional groups, and a one-step method is used to prepare the carbon dot wrapped cuprous oxide nanoplate. The preparation method is simple, convenient, pollution-free, low in technical requirement and highly operable. The obtained carbon dot wrapped cuprous oxide nanoplate has good dispersibility and stability in water due to the large amount of oxygen-containing functional groups of the carbon-based quantum dots on the surface. The composite material has the semiconductor characteristics of cuprous oxide and also contains a large amount of surface defects, and thus has wide application in catalysis, electrocatalysis, photoelectric devices, surface enhanced Raman, antibiosis and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation, specifically relating to a carbon dot-encapsulated cuprous oxide nanoparticle, its preparation method, and its application. Background Technology

[0002] Cuprous oxide is a p-type semiconductor material with a band gap of 2.1 eV. Due to quantum size effects, nano-cuprous oxide exhibits unique optical and electrical properties. Furthermore, as one of the few novel p-type oxide semiconductor materials that can be excited by visible light, nano-cuprous oxide possesses an active electron-hole pair system, exhibiting good catalytic activity and low-temperature paramagnetic properties. Therefore, nano-cuprous oxide has significant applications in organic synthesis, photoelectric conversion, new energy sources, and marine antifouling. Currently, there are many methods for preparing nano-cuprous oxide, such as electrochemical deposition, sol-gel method, hydrothermal method, magnetron sputtering, and chemical deposition. Among these, chemical deposition has attracted much attention due to its simple process and low cost. However, the sizes obtained by current chemical deposition methods are generally large, and they typically exhibit poor stability in aqueous solutions. Monolayer carbon-based dots refer to single-layer nanosheets with a graphene structure and a scale of less than 100 nm. It possesses characteristics such as a large specific surface area and good electron transport capability. Current research has shown that carbon-based dots exhibit Raman enhancement effects, and due to their relatively smooth surface, the Raman signal exhibits good uniformity and reproducibility. Furthermore, their surface often contains numerous hydrophilic groups, such as carboxyl and hydroxyl groups, giving them hydrophilic properties. This invention utilizes monolayer carbon-based dots as encapsulating agents to develop a simple and efficient method for the preparation of cuprous oxide nanosheets. The resulting material exhibits excellent stability. Moreover, the obtained cuprous oxide nanosheets also possess excellent surface-enhanced Raman activity. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing materials by providing a method for preparing carbon-based dot-coated cuprous oxide nanosheets. This method is simple to operate and low in cost. The obtained carbon-based dot-coated cuprous oxide nanosheet composite material exhibits good surface-enhanced Raman activity, enabling the detection of probe molecules with energy level structures matching its conduction band. This can be used for the selective detection of certain environmental pollutants.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing a carbon-based dot-encapsulated cuprous oxide nanosheet surface-enhanced Raman spectroscopy substrate, comprising the following steps:

[0006] (1) Adjust the pH of the carbon-based quantum dot solution to alkaline using alkali;

[0007] (2) Add 300 μL to 500 μL of glucose solution to the solution from step (1);

[0008] (3) After heating the mixed solution obtained in step (2) to boiling, add copper ions while stirring, and keep boiling for 20 minutes;

[0009] (4) Centrifuge the solution obtained in step (3) to collect the precipitate;

[0010] (5) The precipitate obtained after centrifugation in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanosheets.

[0011] The carbon-based dots mentioned in step (1) are graphene nanosheets with a single-layer thickness, a large number of oxygen-containing functional groups on the surface, and a size of less than 100 nm.

[0012] In step (1), the concentration of carbon base points is 0.01 mg / mL to 5 mg / mL.

[0013] In step (1), the alkali used is selected from any one of sodium hydroxide, potassium hydroxide, ammonia, and lithium hydroxide, and the pH value of the solution is in the range of 9-11.

[0014] The copper ions in step (3) are any one of copper chloride, copper nitrate, and copper sulfate, and the molar concentration ratio of copper ions to glucose in step (2) is 1:1 to 1:2.

[0015] The mass concentration ratio of copper ions in step (3) to carbon-based dots in step (2) is 2:1 to 1:5.

[0016] In step (4), the centrifugation speed is 5000~15000 rpm and the centrifugation time is 5~20 min to collect the supernatant.

[0017] The significant advantages of this invention are:

[0018] (1) The preparation method of carbon-based dot-encapsulated cuprous oxide nanosheet surface-enhanced Raman substrate reported in this invention is simple to operate, requires no complicated synthesis steps, uses few reagents, is pollution-free, and has good product stability.

[0019] (2) The carbon-based dot-coated cuprous oxide nanosheets prepared in this invention have uniform thickness and size, making them easy to adsorb analyte molecules. This also broadens the range of materials that can be used for surface-enhanced Raman spectroscopy (SERS) substrates and facilitates mechanism research. Moreover, the SERS activity of the material requires the probe molecules to have an energy level structure that matches their conduction band, so it can be used for the selective detection of certain environmental pollutants. Attached Figure Description

[0020] Figure 1Transmission electron microscope image of the prepared carbon-based dot-encapsulated cuprous oxide nanosheets;

[0021] Figure 2 Atomic force microscopy image of the prepared carbon-based dot-encapsulated cuprous oxide nanosheets;

[0022] Figure 3 The UV-Vis absorption spectrum of cuprous oxide nanosheets encapsulated with carbon-based dots;

[0023] Figure 4 Infrared absorption spectra of carbon-based dots encapsulated cuprous oxide nanosheets;

[0024] Figure 5 Raman signal intensity of crystal violet was detected on a Raman substrate of carbon-based cuprous oxide nanomaterials. Detailed Implementation

[0025] To better understand the present invention, examples are provided for further illustration, but the present invention is not limited thereto.

[0026] Example 1

[0027] (1) Take 1.5 mL of carbon-based solution and dissolve it in 45-50 mL of water; adjust the pH to 10 with sodium hydroxide;

[0028] (2) Add 300 µL of a 1 mol / L glucose solution to the solution from step (1);

[0029] (3) After heating the mixed solution obtained in step (2) to boiling, add 300 µL of prepared copper sulfate solution (1 mol / L) while stirring, and keep boiling for 20 minutes;

[0030] (4) Centrifuge the solution obtained in step (3) at 12000 rpm for 10 min, remove the supernatant and collect the precipitate;

[0031] (5) The precipitate obtained in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanoparticles.

[0032] Example 2

[0033] (1) Take 1.2 mL of carbon-based solution and dissolve it in 45-50 mL of water; adjust the pH to 10 with sodium hydroxide;

[0034] (2) Add 300 µL of a 1 mol / L glucose solution to the solution from step (1);

[0035] (3) After heating the mixed solution obtained in step (2) to boiling, add 300 µL of prepared copper sulfate solution (1 mol / L) while stirring, and keep boiling for 20 minutes;

[0036] (4) Centrifuge the solution obtained in step (3) at 12000 rpm for 10 min, remove the supernatant and collect the precipitate;

[0037] (5) The precipitate obtained in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanoparticles.

[0038] Example 3

[0039] (1) Take 1.2 mL of carbon-based solution and dissolve it in 45-50 mL of water; adjust the pH to 10 with sodium hydroxide;

[0040] (2) Add 325 µL of a 1 mol / L glucose solution to the solution from step (1);

[0041] (3) After heating the mixed solution obtained in step (2) to boiling, add 300 µL of prepared copper sulfate solution (1 mol / L) while stirring, and keep boiling for 20 minutes;

[0042] (4) Centrifuge the solution obtained in step (3) at 12000 rpm for 10 min, remove the supernatant and collect the precipitate;

[0043] (5) The precipitate obtained in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanoparticles.

[0044] Example 4

[0045] (1) Take 1.2 mL of carbon-based solution and dissolve it in 45-50 mL of water; adjust the pH to 10 with sodium hydroxide;

[0046] (2) Add 400 µL of a 1 mol / L glucose solution to the solution from step (1);

[0047] (3) After heating the mixed solution obtained in step (2) to boiling, add 300 µL of prepared copper sulfate solution (1 mol / L) while stirring, and keep boiling for 20 minutes;

[0048] (4) Centrifuge the solution obtained in step (3) at 12000 rpm for 10 min, remove the supernatant and collect the precipitate;

[0049] (5) The precipitate obtained in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanoparticles.

[0050] Example 5

[0051] The material obtained in Example 4 was used as the substrate material for surface-enhanced Raman spectroscopy, and crystal violet was used as the probe molecule for Raman enhancement testing. First, a suitable amount of silicon wafer measuring 0.5 cm × 0.5 cm was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water for 5 min. Then, the silicon wafer, face up, was immersed in a solution of hydrogen peroxide and concentrated sulfuric acid in a 1:4 (volume ratio) solution for several hours. After being removed and cleaned with deionized water, it was immersed face up in a cetyltrimethylammonium bromide (CTAB) solution overnight. Unadsorbed CTAB on the silicon wafer surface was washed away with deionized water. Next, a suitable amount of the material obtained in Example 4 was dropped onto the CTAB-modified silicon wafer, and it was heated to 60°C for complete drying. Finally, 20 μL of a certain concentration of crystal violet standard solution was dropped, and the wafer was heated to 60°C for complete drying. The Raman enhancement effect was then measured using a portable Raman spectrometer.

[0052] Figure 1 Transmission electron microscopy (TEM) image of the prepared carbon-based dot-encapsulated cuprous oxide nanosheets. Figure 1 This indicates that the carbon-based dot-encapsulated cuprous oxide nanosheets prepared by this method are sheet-like with a size of about 60-80 nm, and the nanosheets are surrounded by a layer of carbon-based dots with a thickness of about 2 nm. The nanostructure has clear lattice stripes.

[0053] Figure 2 An atomic force microscope image of the prepared carbon-based dot-encapsulated cuprous oxide nanosheets. Figure 2 This indicates that the prepared cuprous oxide is a thin-layer nanosheet structure.

[0054] Figure 3 The UV-Vis absorption spectrum of cuprous oxide nanosheets encapsulated with carbon-based dots. Figure 3 It can be seen that the ultraviolet absorption of the carbon-based cuprous oxide nanosheet material is between 250 nm and 500 nm. Combined with transmission electron microscopy and atomic force microscopy images, it is further confirmed that the carbon-based cuprous oxide nanosheet material has been synthesized.

[0055] Figure 4 Infrared absorption spectra of carbon-based dots encapsulating cuprous oxide nanosheets. From Figure 4 It can be seen that it is located at approximately 625 cm. -1 The presence of a specific vibrational peak belonging to the Cu-O bond further confirms the synthesis of carbon-based cuprous oxide nanosheets.

[0056] Figure 5 Raman signal intensity of crystal violet was detected on a carbon-based cuprous oxide nanomaterial substrate, with a concentration ranging from 1 × 10⁻⁶. -4 ~5 × 10 -8 mol / L ( Figure 5 a). From Figure 5As can be seen from b, the two-dimensional carbon-based dot-encapsulated cuprous oxide nanosheet substrate exhibits good linearity. Compared with other surface-enhanced Raman substrates, the carbon-based dot-encapsulated cuprous oxide nanosheets show a relatively superior Raman signal.

[0057] The raw materials used in this invention are inexpensive and readily available, the experimental operation is simple and convenient, no special experimental instruments are required, the reaction process is pollution-free, and the finished product has good dispersibility.

[0058] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing carbon dot-encapsulated cuprous oxide nanosheets, characterized in that: Includes the following steps: (1) Adjust the pH of the carbon-based solution to alkaline using alkali; (2) Add glucose solution to the solution from step (1); (3) After heating the mixed solution obtained in step (2) to boiling, add copper ions while stirring, and keep boiling for 20 minutes; (4) Centrifuge the solution obtained in step (3) to collect the precipitate; (5) The precipitate obtained after centrifugation in step (4) is redispersed in secondary water to obtain carbon dot-encapsulated cuprous oxide nanosheets. The carbon-based dots mentioned in step (1) are graphene nanosheets with a single-layer thickness, a large number of oxygen-containing functional groups on the surface, and a size of less than 100 nm.

2. The method for preparing carbon dot-encapsulated cuprous oxide nanosheets according to claim 1, characterized in that: In step (1), the concentration of carbon base points is 0.1 mg / mL to 5 mg / mL.

3. The method for preparing carbon dot-encapsulated cuprous oxide nanosheets according to claim 1, characterized in that: In step (1), the alkali used is any one of sodium hydroxide, potassium hydroxide, or lithium hydroxide, and the pH value of the carbon-based solution is adjusted to be in the range of 9-11.

4. The method for preparing carbon dot-encapsulated cuprous oxide nanosheets according to claim 1, characterized in that: The copper ions in step (3) are any one of copper chloride, copper nitrate, and copper sulfate, and the molar concentration ratio of copper ions to glucose in step (2) is 1:1 to 1:

2.

5. The method for preparing carbon dot-encapsulated cuprous oxide nanosheets according to claim 1, characterized in that: The mass concentration ratio of copper ions in step (3) to carbon-based dots in step (2) is 2:1 to 1:

5.

6. The method for preparing carbon dot-encapsulated cuprous oxide nanosheets according to claim 1, characterized in that: In step (4), the centrifugation speed is 5000~15000 rpm and the centrifugation time is 5~20 min to collect the supernatant.

7. A carbon dot-encapsulated cuprous oxide nanosheet prepared by the preparation method according to any one of claims 1-6.

8. The application of carbon dot-encapsulated cuprous oxide nanosheets as described in claim 7 in surface-enhanced Raman spectroscopy.

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