Graphene quantum dot preparation method and device based on graphene oxide precursor

Abstract

The invention discloses a graphene quantum dot preparation method and device based on a graphene oxide precursor, and the method comprises the steps: firstly dissolving graphene oxide in deionized water, and carrying out ultrasonic dispersion to obtain a graphene oxide aqueous solution; dialyzing the graphene oxide aqueous solution to remove ion impurities; ultrasonic cavitation is generated through an ultrasonic device, and graphene quantum dots are prepared from graphene oxide; and finally, taking out the treated graphene dispersion liquid, and dialyzing to obtain a graphene quantum dot solution. According to the method, the graphene quantum dots are prepared by strong ultrasound under high hydrostatic pressure, and the strong ultrasound under the high hydrostatic pressure can generate a stronger ultrasonic cavitation effect than ordinary ultrasound under normal pressure, so that stronger force and chemical action can be generated, and the graphene quantum dots can be prepared by utilizing an ultrasonic amplitude-change pole under the condition of no chemical addition. The graphene quantum dots are prepared from graphene oxide. The defect that dangerous chemicals are added or other impurities are introduced in a traditional GQDs preparation method is overcome.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to a method and a device for preparing graphene quantum dots based on a graphene oxide precursor. Background Art

[0002] Graphene Quantum Dots (GQDs) have become a graphene-based material that has attracted much attention due to their excellent chemical, physical and biological properties. They have been widely used in many fields such as biomedical imaging, sensors, optoelectronic devices, drug delivery and cell imaging. At present, the preparation methods of GQDs mainly include chemical oxidation, hydrothermal, electrochemical and ultrasonic-assisted methods. Among them, the ultrasonic-assisted method has attracted widespread attention due to its simple operation and low equipment requirements.

[0003] However, existing ultrasonic-assisted methods generally require the addition of chemicals such as oxidants and reductants for the exfoliation of graphite or graphite oxide. This not only increases the complexity of the preparation process, but also introduces impurities, resulting in a cumbersome purification process and reduced yield and efficiency. In addition, residual chemical reagents during the preparation process may affect the performance and application safety of quantum dots. Therefore, how to simplify the preparation process, reduce the use of chemicals, and improve sample purity and performance remains a technical problem that needs to be solved urgently.

[0004] Therefore, there is an urgent need for a method for preparing graphene quantum dots that does not rely on chemical reagents, does not introduce impurities, is fast, convenient, has a simple process flow, and is environmentally friendly. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a method and apparatus for preparing graphene quantum dots based on a graphene oxide precursor, wherein the method uses strong ultrasound generated by an ultrasonic horn under high hydrostatic pressure to prepare graphene quantum dots from graphene oxide.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: The method for preparing graphene quantum dots based on graphene oxide precursor provided by the present invention comprises the following steps: S1, dissolving graphene oxide in deionized water to obtain a graphene oxide aqueous solution, and using an ultrasonic cleaner to ultrasonically disperse the graphene oxide aqueous solution to obtain a graphene oxide aqueous solution with good dispersibility; S2, dialyzing the graphene oxide aqueous solution to remove various ionic impurities; S3, preparing graphene quantum dots from graphene oxide by applying ultrasonic waves generated by an ultrasonic device to a graphene oxide aqueous solution; S4. Taking out the treated graphene dispersion and dialyzing it to obtain a graphene quantum dot solution with high water dispersibility.

[0007] Furthermore, the ultrasonic dispersion time in step S1 is 1-4 hours.

[0008] Furthermore, in step S2, the dialysis time is to replace the dialysis external solution every 2-6 hours, for a total of 30-50 hours of dialysis.

[0009] Furthermore, the dialysis in step S2 is performed using a dialysis bag; the use of the dialysis bag allows the permeation molecular weight to be 8-14 kDa.

[0010] Furthermore, the ultrasonic device in step S3 is a high hydrostatic pressure ultrasonic horn device, and the graphene oxide aqueous solution is treated by the high hydrostatic pressure ultrasonic horn device.

[0011] Further, in step S3, the preparation of graphene quantum dots from graphene oxide by ultrasound is carried out according to the following steps: S31, placing the prepared graphene oxide solution in a high pressure chamber; S32, increasing the pressure in the cabin by means of a pressurizing device to further increase the ultrasonic cavitation intensity; applying high hydrostatic pressure to the hyperbaric cabin; S33, placing the ultrasonic horn in a high-pressure chamber filled with liquid medium, and setting the working parameters of the horn, which include frequency, driving power, and action time.

[0012] Furthermore, in step S4, the treated graphene dispersion is taken out and dialyzed, and the dialyzed liquid is concentrated by rotary evaporation to obtain a graphene quantum dot solution with high water dispersibility.

[0013] Furthermore, the ultrasonic device adopts a high hydrostatic pressure ultrasonic horn device, and the high hydrostatic pressure ultrasonic horn device includes a high pressure chamber, a reaction container, an ultrasonic horn, a power source, and a pressurizing device; The high-pressure chamber is used to contain the prepared graphene oxide solution; The ultrasonic horn is used to generate ultrasonic waves, is placed in a high-pressure chamber, and processes the graphene oxide aqueous solution, and the graphene oxide is prepared into graphene quantum dots by the strong ultrasound generated by the ultrasonic horn; The power source is used to provide a stable power supply for the ultrasonic horn device; The pressurizing device is used to apply high hydrostatic pressure to the hyperbaric chamber to increase the pressure inside the chamber.

[0014] Furthermore, the high hydrostatic pressure applied by the pressurizing device to the hyperbaric chamber is 0.1-5 MPa.

[0015] The beneficial effects of the present invention are: The graphene quantum dot preparation method based on graphene oxide precursor and high hydrostatic pressure ultrasonic horn device provided by the present invention can produce stronger force and chemical action due to the strong ultrasound under high hydrostatic pressure will produce stronger ultrasonic cavitation effect than ordinary ultrasound under normal pressure, so as to realize the preparation of graphene quantum dots from graphene oxide in one step by using ultrasonic horn without chemical addition. This method overcomes the problem that the traditional GQDs preparation method will add dangerous chemicals or introduce other impurities, which brings difficulties to the subsequent purification and application of GQDs.

[0016] The ultrasonic treatment method using an ultrasonic horn under high hydrostatic pressure provided by the present invention is used to directly prepare graphene quantum dots from graphite oxide, without adding hazardous chemicals and subsequent cumbersome purification treatment, to prepare graphene quantum dots with high water dispersibility and resistance to photobleaching; the method does not add chemical reagents, does not introduce impurities, and has a simple process flow and is an environmentally friendly method for preparing GQDs. The graphene quantum prepared by the method has a micron scale, low impurity content, good dispersibility, and good resistance to photobleaching, and can be functionalized and serve the fields of biology and sensing.

[0017] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for explanation.

[0019] Figure 1 Flowchart for the preparation of graphene quantum dots.

[0020] Figure 2 Schematic diagram of the high hydrostatic pressure ultrasonic horn device.

[0021] In the figure, there is a high-pressure chamber 1, a graphene oxide aqueous solution 2, an ultrasonic horn 3, a power source 4, and a pressurizing device 5. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0023] Example 1 like Figure 1 As shown, the method for preparing graphene quantum dots based on graphene oxide precursor provided in this embodiment specifically includes the following steps: S1, dissolving graphene oxide in deionized water to obtain a graphene oxide aqueous solution, and using an ultrasonic cleaning machine to ultrasonically disperse the graphene oxide aqueous solution to obtain a graphene oxide aqueous solution with good dispersibility; In this embodiment, the ultrasonic dispersion time is 1-4 hours; in this embodiment, the dispersion time is 1 hour.

[0024] The original size of the graphene oxide described in step S1 is 0.5-5 μm; The ultrasonic cleaning machine described in step S1 has an ultrasonic power of 300-980 W and a temperature range of 15-80 °C; S2, dialyzing the graphene oxide aqueous solution to remove various ionic impurities; The dialysis time in this embodiment is to replace the dialysis external solution every 2-6 hours, for a total of 30-50 hours; In this embodiment, the dialysis fluid was replaced every 4 hours, for a total of 48 hours. The dialysis bag used in step S2 allows a molecular weight of 8 to 14 kDa; The dialysis in this embodiment is performed using a dialysis bag; S3, preparing graphene quantum dots from graphene oxide by ultrasonic cavitation using strong ultrasound generated by an ultrasonic device; The ultrasonic device in this embodiment is a high hydrostatic pressure ultrasonic horn device, and the graphene oxide aqueous solution is treated by the high hydrostatic pressure ultrasonic horn device, that is, the graphene quantum dots are prepared from the graphene oxide by the strong ultrasound generated by the ultrasonic horn under high hydrostatic pressure; the high hydrostatic pressure is set to 0.1-5 MPa; The ultrasonic action time is ≥ 30 min; or the action time is 30-90 min; In this embodiment, the ultrasonic wave prepares graphene oxide into graphene quantum dots according to the following steps: S31, placing the prepared graphene oxide solution in a high pressure chamber; S32, increasing the pressure in the cabin by means of a pressurizing device to further increase the ultrasonic cavitation intensity; applying high hydrostatic pressure to the hyperbaric cabin; S33, placing the ultrasonic horn in the high-pressure chamber, and setting the working parameters of the horn, wherein the working parameters include frequency, driving power, and action time; The frequency is 20kHz~80kHz; The driving power is 1000~000W, The hydrostatic pressure is 0.1-5 MPa, and the action time is 30-90 min, and the action time can be pulsed or continuous; S4, taking out the treated graphene dispersion, dialyzing it, and concentrating the dialyzed liquid by rotary evaporation to obtain a graphene quantum dot solution with high water dispersibility; The dialysis permeate molecular weight in step S4 is 8-14 kDa; The water bath temperature of the rotary evaporation equipment described in step S4 is 30-80°C.

[0025] The dialysis in this embodiment is performed using a dialysis bag.

[0026] Example 2 like Figure 2 As shown, Figure 2 The high hydrostatic pressure ultrasonic horn device is a structural diagram, wherein the high hydrostatic pressure ultrasonic horn device comprises a high pressure chamber, an ultrasonic horn, a power source and a pressurizing device; The high-pressure chamber is used to contain the prepared graphene oxide solution; The ultrasonic horn is used to generate ultrasonic waves and is placed in a high-pressure chamber filled with liquid medium. The graphene oxide aqueous solution is treated, and strong ultrasound is generated by the ultrasonic horn to prepare graphene quantum dots from graphene oxide; the horn frequency is 20kHz~80kHz, which can be selected according to actual needs. In order to produce more intense cavitation, high frequency is preferred; Since strong ultrasound under high hydrostatic pressure produces a stronger ultrasonic cavitation effect than ordinary ultrasound under normal pressure, it can produce stronger force and chemical action, thus breaking large flake graphene into small-sized graphene or even graphene quantum dots. The power source is used to provide a stable power supply to the ultrasonic horn device to ensure its normal operation; The pressurizing device is used to apply high hydrostatic pressure (0.1-5 MPa) to the hyperbaric chamber to increase the pressure inside the chamber and further increase the ultrasonic cavitation intensity; In this embodiment, the driving power of the high hydrostatic pressure ultrasonic horn device is ≥ 1000 W, the hydrostatic pressure is 0.1~5 MPa, the action time is ≥ 30 min, the action time can be pulsed or continuous, and the duty cycle can be adjusted according to actual requirements; The specific process of the method for preparing graphene quantum dots based on graphene oxide precursor in this example is as follows: 200 mg of graphene oxide was dissolved in 40 ml of deionized water, wherein the size of graphene oxide powder was 0.5-5 μm; The mixed graphene oxide solution was placed in an ultrasonic cleaning machine with an ultrasonic power of 600 W for ultrasonic dispersion for 1 hour, and then taken out to obtain a graphene oxide aqueous solution with good water dispersibility; The dispersed graphene solution was placed in a dialysis bag with a molecular weight of 8-14 kDa for dialysis. The dialysis external solution was replaced every 4 hours for a total of 48 hours. The dialyzed graphene oxide quantum dot solution was placed under high hydrostatic pressure and ultrasonically treated using an ultrasonic horn device with ultrasonic parameters of 1000W and 5MPa. The total operating time was 6 h, with ultrasound acting for 1 s and stopping for 9 s. The graphene solution after ultrasonic treatment is dialyzed using a dialysis bag with a molecular weight of 8-14 kDa, and the dialyzate is concentrated by rotary evaporation to obtain graphene quantum dots with high water dispersibility.

[0027] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing graphene quantum dots based on a graphene oxide precursor, characterized in that: The following steps are involved: S1, dissolving graphene oxide in deionized water to obtain a graphene oxide aqueous solution, and using an ultrasonic cleaning machine to ultrasonically disperse the graphene oxide aqueous solution to obtain a graphene oxide aqueous solution with good dispersibility; S2, dialyzing the graphene oxide aqueous solution to remove ionic impurities; S3, generating ultrasonic cavitation by an ultrasonic device to prepare graphene quantum dots from graphene oxide; S4. Taking out the treated graphene dispersion and dialyzing it to obtain a graphene quantum dot solution with high water dispersibility.

2. The method for preparing graphene quantum dots based on a graphene oxide precursor according to claim 1, characterized in that: The ultrasonic dispersion time in step S1 is 1-4 hours.

3. The method for preparing graphene quantum dots based on graphene oxide precursor according to claim 1, characterized in that: The dialysis time in step S2 is to replace the dialysis external solution every 2-6 hours, for a total of 30-50 hours of dialysis.

4. The method for preparing graphene quantum dots based on graphene oxide precursor according to claim 1, characterized in that: The dialysis in step S2 is performed using a dialysis bag; the dialysis bag allows the permeation molecular weight to be 8-14 kDa.

5. The method for preparing graphene quantum dots based on graphene oxide precursor according to claim 1, characterized in that: The ultrasonic device in step S3 is a high hydrostatic pressure ultrasonic horn device, and the graphene oxide aqueous solution is treated by the high hydrostatic pressure ultrasonic horn device.

6. The method for preparing graphene quantum dots using a graphene oxide precursor according to claim 5, characterized in that: In step S3, the preparation of graphene quantum dots from graphene oxide by ultrasonic wave is carried out according to the following steps: S31, placing the prepared graphene oxide solution in a high pressure chamber; S32, increasing the pressure in the cabin by means of a pressurizing device to increase the intensity of ultrasonic cavitation; S33, placing the ultrasonic horn in the high-pressure chamber, and setting the working parameters of the horn, wherein the working parameters include frequency, driving power, and action time.

7. The method for preparing graphene quantum dots based on graphene oxide precursor according to claim 1, characterized in that: In the step S4, the treated graphene dispersion is taken out and dialyzed, and the dialyzed liquid is concentrated by rotary evaporation to obtain a graphene quantum dot solution with high water dispersibility.

8. A device for implementing the method for preparing graphene quantum dots based on graphene oxide precursor according to any one of claims 1 to 7, characterized in that: The device is a high hydrostatic pressure ultrasonic horn device, which comprises a high pressure chamber, a reaction vessel, an ultrasonic horn, a power source and a pressurizing device; The high-pressure chamber is used to contain the prepared graphene oxide solution; The ultrasonic horn is used to generate ultrasonic cavitation, and is placed in a high-pressure chamber filled with a liquid medium to treat the graphene oxide aqueous solution, and prepare graphene quantum dots from the graphene oxide through the strong ultrasound generated by the ultrasonic horn under high hydrostatic pressure; The power source is used to provide a stable power supply for the ultrasonic horn device; The pressurizing device is used to apply high hydrostatic pressure to the hyperbaric chamber, thereby increasing the pressure inside the chamber and improving the ultrasonic cavitation intensity.

9. The graphene quantum dot preparation device based on graphene oxide precursor according to claim 8, characterized in that: The high hydrostatic pressure applied by the pressurizing device to the hyperbaric chamber is 0.1~5 MPa.

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