Size grading method for graphene material

A grading method and graphene technology, applied in the field of graphene materials, can solve the problems of inability to separate large and small pieces of graphene oxide, insufficiently uniform pore size distribution, long pore channels, etc., and achieve the effect of significant size separation effect.

Inactive Publication Date: 2015-08-05
TSINGHUA UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

The reasons or problems mainly include the following two points: 1. The pore structure of ordinary filter membranes is intertwined, the pores are long, and the pore size distribution is not uniform enough, which will cause graphene oxide to remain in the pores and block the pores, making it impossible to separate large and small pieces of graphene oxide; 2. Even if a suitable membrane material is selected to avoid the above problems, graphene oxide is easy to stack on the surface of the membrane due to its two-dimensional sheet nature, resulting in blocking the pores from the surface of the membrane

Method used

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  • Size grading method for graphene material
  • Size grading method for graphene material
  • Size grading method for graphene material

Examples

Experimental program
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Effect test

Embodiment 1

[0047] Embodiment 1, grading graphene oxide sheet according to size:

[0048] 1) Preparation of graphene oxide: 1.0 g of 325 mesh natural graphite powder was mixed with 23 mL of 96-98 wt % concentrated sulfuric acid in an ice-water bath, and after stirring evenly, 9.0 g of potassium permanganate was slowly added. Raise the temperature of the system to 35°C, keep it stable for half an hour, add 50mL deionized water, continue stirring for 15 minutes, add 150mL deionized water, 5mL 3wt% H 2 o 2 . The resulting bright yellow solution was filtered and washed with 100 mL of aqueous HCl (wherein the volume ratio of hydrochloric acid and water was 1:9). The resulting solid was dried in air and diluted, dialyzed in deionized water for one week, then ultrasonically stripped, and centrifuged twice at 3000rpm for 30min to remove the substrate to obtain a dispersion of monolayer graphene oxide;

[0049] 2) Grading graphene oxide flakes according to size: the dispersion of single-layer g...

Embodiment 2

[0066] Embodiment 2, classifying graphene oxide sheet according to size:

[0067] Using the dispersion of single-layer graphene oxide prepared in Example 1 as raw material, dilute it to 0.2 mg / mL, and use only a 3.5 μm membrane to separate the two components. The obtained results are as follows: Figure 8 As shown, the size difference between the obtained two components is obvious, and more than 90% of the size distribution of the 3.5 μm filter is smaller than 7 μm, while more than 90% of the intercepted size is larger than 6 μm.

Embodiment 3

[0068] Embodiment 3, classifying graphene oxide sheet according to size:

[0069] Using the dispersion of single-layer graphene oxide prepared in Example 1 as a raw material, dilute it to 0.2 mg / mL, and only use a 5.5 μm membrane to separate the two components. The obtained results are as follows: Figure 9 As shown, the size difference between the two components obtained is obvious, and more than 90% of the size distribution of the 5.5 μm filter is smaller than 11 μm, while more than 90% of the intercepted size is larger than 9 μm;

[0070] Moreover, after being rinsed with a simple solvent (such as water and ethanol, etc.) after use, the filter membrane can be used repeatedly without graphene oxide (GO) residues (such as Figure 10 ), Figure 10 The picture in the upper middle row is the SEM image of the unused filter membrane, Figure 10 The pictures in the middle and lower rows are SEM images of the used and washed filter membranes.

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Abstract

The invention relates to a graphene oxide size grading method. The method includes the steps of: 1) dispersing a graphene material in a solvent to obtain a graphene material dispersion liquid; 2) under the condition of an externally applied force, passing the graphene material dispersion liquid through a porous membrane to obtain filtrate and trapped fluid, and conducting separation to obtain graphene materials with different size ranges. Based on the correlation of graphene material size and separation membrane pore size, the method disturbs the graphene material solution to prevent pore channel blockage, and realizes physical one-step method size grading of the graphene material (e.g. graphene oxide). By selecting multiple pore sizes and separation number of times, the graphene material can be separated into a lot of grades according to size. The one-step method for size grading of graphene material is simple, effective, cheap and environment-friendly, and can be used on a large scale. At the same time, the filter membrane for separation can be used repeatedly, thus saving cost.

Description

technical field [0001] The invention belongs to the technical field of graphene materials, in particular to a size classification method for graphene materials. Background technique [0002] Graphene, that is, single-layer graphite, is made of sp 2 A new type of carbon material in which hybridized carbon atoms are interconnected to form a two-dimensional honeycomb structure with a monolayer thickness. Graphene's unique electrical, optical, mechanical, and thermal properties make it have great application prospects in electronics, structural materials, energy storage materials, sensing materials, catalytic materials, and composite materials. In the process of regulating the properties and applications of graphene, the size of graphene sheets plays a key role. Large-scale graphene sheets are widely used in the preparation of three-dimensional network structures, two-dimensional ordered stacked layered structures, and optoelectronic devices; and in fields that require high bi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/04
Inventor 石高全陈骥
Owner TSINGHUA UNIV
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