Preparation method of nano graphene oxide

Abstract

The invention discloses a preparation method of nano graphene oxide, which comprises the following steps: (1) dispersing graphene oxide in deionized water to obtain a graphene oxide dispersion liquid; (2) irradiating the graphene oxide dispersion liquid prepared in the step (1) to obtain a porous graphene oxide dispersion liquid; (3) adding peroxide into the porous graphene oxide dispersion liquid prepared in the step (2) to obtain mixed liquid; (4) heating and stirring the mixed solution obtained in the step (3) for reaction to obtain nano graphene oxide dispersion liquid; and (5) performing freeze drying on the nano graphene oxide dispersion liquid prepared in the step (4) to obtain nano graphene oxide powder. The average size of the nano graphene oxide prepared by the method is 20-80 nm; the average thickness is 1-3nm, the water dispersibility is excellent, and the absolute value of Zeta potential is not less than 20mV.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene, and in particular relates to a method for preparing nano graphene oxide. Background Art

[0002] Graphene oxide is one of the important derivatives of graphene. Compared with graphene, it has more oxygen-containing functional groups. These functional groups not only provide good water dispersibility, but also provide more modification sites for graphene oxide, making it easy to compound with other materials and form a good interface. Therefore, the research on graphene oxide has always been one of the hot spots in the field of graphene material research.

[0003] As a two-dimensional material, the common size of graphene oxide is at the micron level to show its two-dimensional material characteristics. Nanoscale graphene oxide usually refers to graphene oxide with a sheet diameter of less than 100 nanometers. Compared with micron-scale graphene oxide, nanoscale graphene oxide has better dispersibility, higher specific surface area and more edges. Its nanoscale size enables it to penetrate cell membranes, and the quantum effect and size effect also give it certain fluorescent properties. These characteristics make nanoscale graphene oxide have broad application prospects in materials science and biomedicine.

[0004] At present, there are limited methods for preparing nano-graphene oxide, including separating a small amount of nano-graphene oxide by size separation technology, ultrasonically crushing graphene oxide sheets, and chemically cutting graphene nanofibers. These methods all achieve the cutting and crushing of graphene oxide by applying external energy. However, this crushing method has problems such as poor controllability and high energy consumption because it involves random oxidation and cutting of graphene oxide sheets.

[0005] Therefore, developing a new method for preparing nanographene oxide that is fast, low-cost, has a low number of layers, and has uniform size distribution is one of the problems that need to be solved in the field of graphene. This breakthrough will help promote the application and development of graphene oxide in various fields. Summary of the invention

[0006] The present invention aims to overcome the defects of the prior art and provide a method for preparing nano-graphene oxide.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing nano graphene oxide comprises the following steps:

[0009] (1) dispersing graphene oxide in deionized water to obtain a graphene oxide dispersion;

[0010] (2) irradiating the graphene oxide dispersion obtained in step (1) to obtain a porous graphene oxide dispersion;

[0011] (3) adding peroxide to the porous graphene oxide dispersion prepared in step (2) to obtain a mixed solution;

[0012] (4) heating and stirring the mixed solution obtained in step (3) to react, thereby obtaining a nano-graphene oxide dispersion;

[0013] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) to obtain nano-graphene oxide powder.

[0014] In a preferred embodiment of the present invention, the dispersion method in step (1) is 20-40 kHz high-frequency ultrasonic dispersion, and the concentration of the graphene oxide dispersion is 0.1-0.5 mg / mL.

[0015] Further preferably, the dispersion method in step (1) is 25-30 kHz high-frequency ultrasonic dispersion, and the concentration of the graphene oxide dispersion is 0.1-0.2 mg / mL.

[0016] In a preferred embodiment of the present invention, the irradiation is selected from the group consisting of xenon lamp irradiation, high pressure mercury lamp irradiation, LED irradiation, ultraviolet irradiation and natural sunlight irradiation.

[0017] In a preferred embodiment of the present invention, the peroxide is selected from hydrogen peroxide, peracetic acid, sodium persulfate and ammonium persulfate, and the mass ratio of the graphene oxide to the peroxide is 1:10-5000.

[0018] Further preferably, the mass ratio of the graphene oxide to the peroxide is 1:2000-3000.

[0019] In a preferred embodiment of the present invention, in step (4), the temperature of the heating and stirring reaction is 25-80°C, and the stirring speed is 200-600r / min.

[0020] Further preferably, in step (4), the temperature of the heating and stirring reaction is 25-70°C.

[0021] In a preferred embodiment of the present invention, in the step (5), the freeze-drying time is 48-60 hours.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention utilizes the photochemical activity of graphene oxide itself for preparation. Figure 1As shown in the figure, due to the presence of oxygen-containing functional groups, the zero band gap of graphene is broken, so that after irradiation, the valence band electrons can jump to the conduction band, generating hole-electron pairs. The free electrons will combine with some oxygen-containing functional groups and leave, leaving a strong oxidizing hole. These holes will further oxidize the defective carbon, resulting in the formation of a porous structure. Figure 2 As shown, this porous structure is sensitive to peroxide and will be transformed into a fragmented structure in the presence of peroxide. Under this conversion condition, the porous graphene oxide is still dispersed in the solution in the form of a single layer, and no other crushing and peeling means are required. The holes generated by its own optical activity are evenly distributed on the surface. Therefore, the nano-graphene oxide prepared by using this characteristic has fewer layers and more uniform size distribution. In other words, the present invention not only simplifies the preparation process, but also improves the quality of nano-graphene oxide, so that it exhibits better performance in applications.

[0024] 2. The nano-graphene oxide prepared by the present invention has an average size of 20 to 80 nm, an average thickness of 1 to 3 nm, and has excellent water dispersibility, and the absolute value of the Zeta potential is not less than 20 mV. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The process of forming porous graphene oxide after irradiation of graphene oxide in the present invention is shown.

[0026] Figure 2 The process of porous graphene oxide being induced by hydrogen peroxide in the present invention is shown.

[0027] Figure 3 The transmission electron microscope scanning result (a) and the atomic force microscope scanning result (b) of the graphite oxide dispersion prepared in Example 1 of the present invention are shown.

[0028] Figure 4 The flake size distribution of the graphene oxide dispersion in Example 1 of the present invention is shown.

[0029] Figure 5 The transmission electron microscope scanning results (a) and the atomic force microscope scanning results (b) of the porous graphene oxide dispersion prepared in Example 1 of the present invention are shown.

[0030] Figure 6 Shown a are the transmission electron microscope scanning results (a) and atomic force microscope scanning results (b) of the nano-graphene oxide dispersion prepared in Example 1 of the present invention.

[0031] Figure 7 The flake size distribution of nano-graphene oxide in the nano-graphene oxide dispersion prepared in Example 1 of the present invention is shown.

[0032] Figure 8The Zeta potential analysis of the nano-graphene oxide prepared in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0034] Example 1

[0035] (1) 50 mg of graphene oxide was dispersed in 50 mL of deionized water by 25-30 kHz high-frequency ultrasonic treatment to obtain Figure 3 and 4 The graphene oxide dispersion shown has a concentration of 0.1 mg / mL;

[0036] (2) The graphene oxide dispersion obtained in step (1) was transferred to a quartz bottle, and the quartz bottle was placed under a xenon lamp for 72 hours, and the xenon lamp light source intensity was 1 sun intensity, and a brown-black color was obtained. Figure 5 The porous graphene oxide dispersion shown;

[0037] (3) transferring the porous graphene oxide dispersion obtained in step (2) into a beaker, adding 10 mL of hydrogen peroxide (mass concentration of 30%) to obtain a mixed solution;

[0038] (4) The mixed solution obtained in step (3) was heated to 50°C, the stirring speed was set to 200 r / min, and stirred for 6 h to obtain Figures 6 to 8 Nano-graphene oxide dispersion shown;

[0039] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) for 48 hours to obtain nano-graphene oxide powder.

[0040] The nano-graphene oxide prepared in this embodiment has an average size of 35 nm, an average layer thickness of 1.2 nm, and a Zeta potential of -39.4 mV after being dispersed in water.

[0041] Example 2

[0042] (1) dispersing 200 mg of graphene oxide in 100 mL of deionized water by 25-30 kHz high-frequency ultrasonic treatment to obtain a graphene oxide dispersion with a concentration of 0.2 mg / mL;

[0043] (2) transferring the graphene oxide dispersion obtained in step (1) into a quartz culture dish, placing it in a high-pressure mercury lamp oven, turning on the high-pressure mercury lamp at a distance of 13 cm from the lamp tube, and irradiating for 20 minutes to obtain a brown-black porous graphene oxide dispersion;

[0044] (3) transferring the porous graphene oxide dispersion obtained in step (2) into a beaker, adding 5 mL of peracetic acid to obtain a mixed solution;

[0045] (4) stirring the mixed solution obtained in step (3) at room temperature (25° C.) at a stirring speed of 500 r / min for 72 h to obtain a nano-graphene oxide dispersion;

[0046] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) for 36 hours to obtain nano-graphene oxide powder.

[0047] The nano-graphene oxide prepared in this embodiment has an average size of 25 nm and an average thickness of 1.3 nm. After being dispersed in water, the Zeta potential is -32.1 mV.

[0048] Example 3

[0049] (1) dispersing 50 mg of graphene oxide in 50 mL of deionized water by 25-30 kHz high-frequency ultrasonic treatment to obtain a graphene oxide dispersion with a concentration of 0.1 mg / mL;

[0050] (2) The graphene oxide dispersion obtained in step (1) was transferred to a quartz bottle, and the quartz bottle was placed under an LED light source for 72 h (the LED light source intensity was 200 mW / cm 2 ), to obtain a brown-black porous graphene oxide dispersion;

[0051] (3) transferring the porous graphene oxide dispersion obtained in step (2) into a beaker, adding 0.28 g of ammonium persulfate to obtain a mixed solution;

[0052] (4) heating the mixed solution obtained in step (3) to 70° C., setting the stirring speed to 350 r / min, and stirring for 48 h to obtain a nano-graphene oxide dispersion;

[0053] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) for 24 hours to obtain nano-graphene oxide powder.

[0054] The nano-graphene oxide prepared in this embodiment has an average size of 42 nm, an average layer thickness of 1.1 nm, and a Zeta potential of -33.4 mV after being dispersed in water.

[0055] Example 4

[0056] (1) dispersing 300 mg of graphene oxide in 100 mL of deionized water by 25-30 kHz high-frequency ultrasonic treatment to obtain a graphene oxide dispersion with a concentration of 0.3 mg / mL;

[0057] (2) transferring the graphene oxide dispersion obtained in step (1) into a quartz bottle, placing the quartz bottle under a 365 nm ultraviolet light source for 55 h to obtain a brown-black porous graphene oxide dispersion;

[0058] (3) transferring the porous graphene oxide dispersion obtained in step (2) into a beaker, adding 0.23 g of sodium persulfate to obtain a mixed solution;

[0059] (4) heating the mixed solution obtained in step (3) to 45° C., setting the stirring speed to 600 r / min, and stirring for 48 h to obtain a nano-graphene oxide dispersion;

[0060] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) for 48 hours to obtain nano-graphene oxide powder.

[0061] The nano-graphene oxide prepared in this embodiment has an average size of 28 nm, an average layer thickness of 1.7 nm, and a Zeta potential of -26.7 mV after being dispersed in water.

[0062] Example 5

[0063] (1) dispersing 200 mg of graphene oxide in 200 mL of deionized water by 25-30 kHz high-frequency ultrasonic treatment to obtain a graphene oxide dispersion with a concentration of 0.1 mg / mL;

[0064] (2) transferring the graphene oxide dispersion obtained in step (1) into a quartz bottle, placing the quartz bottle under natural light for 60 hours (the natural light intensity at noon is about the intensity of one sun), and obtaining a brown-black porous graphene oxide dispersion;

[0065] (3) transferring the porous graphene oxide dispersion obtained in step (2) into a beaker, adding 40 mL of hydrogen peroxide (30%) to obtain a mixed solution;

[0066] (4) placing the mixed solution obtained in step (3) at room temperature of 25° C., setting the stirring speed to 450 r / min, and stirring for 72 h to obtain a nano-graphene oxide dispersion;

[0067] (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) for 48 hours to obtain nano-graphene oxide powder.

[0068] The nano-graphene oxide prepared in this embodiment has an average size of 21 nm, an average layer thickness of 1.3 nm, and a Zeta potential of -38.6 mV after being dispersed in water.

[0069] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing nano graphene oxide, characterized in that: The steps include: (1) dispersing graphene oxide in deionized water to obtain a graphene oxide dispersion; (2) irradiating the graphene oxide dispersion obtained in step (1) to obtain a porous graphene oxide dispersion; (3) adding peroxide to the porous graphene oxide dispersion prepared in step (2) to obtain a mixed solution; (4) heating and stirring the mixed solution obtained in step (3) to react, thereby obtaining a nano-graphene oxide dispersion; (5) freeze-drying the nano-graphene oxide dispersion obtained in step (4) to obtain nano-graphene oxide powder.

2. The preparation method according to claim 1, characterized in that: The dispersion method of step (1) is 20-40kHz high-frequency ultrasonic dispersion, and the concentration of the graphene oxide dispersion is 0.1-0.5 mg / mL.

3. The preparation method according to claim 2, characterized in that: The dispersion method of step (1) is 25-30kHz high-frequency ultrasonic dispersion, and the concentration of the graphene oxide dispersion is 0.1-0.2 mg / mL.

4. The preparation method according to claim 1, characterized in that: The irradiation is selected from xenon lamp irradiation, high pressure mercury lamp irradiation, LED irradiation, ultraviolet irradiation and natural sunlight irradiation.

5. The preparation method according to claim 1, characterized in that: The peroxide is selected from hydrogen peroxide, peracetic acid, sodium persulfate and ammonium persulfate, and the mass ratio of the graphene oxide to the peroxide is 1:10-5000.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the graphene oxide to the peroxide is 1:2000-3000.

7. The preparation method according to claim 1, characterized in that: In the step (4), the temperature of the heating and stirring reaction is 25-80°C, and the stirring speed is 200-600r / min.

8. The preparation method according to claim 7, characterized in that: In the step (4), the temperature of the heating and stirring reaction is 25-70°C.

9. The preparation method according to claim 1, characterized in that: In the step (5), the freeze-drying time is 48-60 hours.

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