Method for preparing large-scale graphene through supercritical carbon dioxide exfoliation

Abstract

The invention relates to a method for preparing large-scale graphene through supercritical carbon dioxide exfoliation. Supercritical carbon dioxide is adopted as an exfoliant, a surfactant is adopted as a dispersant, graphite powder and the dispersant are put in an autoclave, the carbon dioxide is pumped in the autoclave and circularly flows in a supercritical state, and then the pressure is reduced quickly to be normal pressure; the process is repeated so that the materials undergo pressure increment and pressure reduction several times; and the layers of the graphene is controlled by controlling the times of pressure increment and pressure reduction, so as to prepare the large scale graphene. Compared with the prior art, the invention has the advantages as follows: large-scale (hundreds of micrometers) high-quality graphene can be prepared; the method belongs to physical exfoliation, the treatment conditions are mild, and the quality of the graphene cannot be damaged; besides, the carbon dioxide used in the method is nontoxic, cheap and easy to obtain, and the technology is simple.

Description

technical field [0001] The invention belongs to the technical field of preparation of functional materials, and in particular relates to a method for preparing large-scale graphene by exfoliating supercritical carbon dioxide. Background technique [0002] Graphene is a two-dimensional crystal composed of carbon atoms, in which the carbon atoms are sp 2 Hybridization forms a honeycomb hexagonal planar structure. Graphene has excellent mechanical and electrical properties, and has broad application prospects in electronics, magnetism, optics, biology, etc. Since it was discovered by scientists from the University of Manchester in 2004, it has attracted extensive attention from researchers in the fields of physics, materials and chemistry, especially after the discoverer of graphene won the Nobel Prize in 2010, the preparation and properties of graphene And the research on application and other aspects has become a hot spot concerned by scholars from all over the world. [0...

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Problems solved by technology

But this method output is extremely low, has no production value; Oxidation-reduction method is the method that uses more at present, and Chinese patent (application number: 200910099595.x) discloses " a kind of solution phase preparation method of graphene " although this method can Graphene with a large area is prepared, but this method will introduce a large number of defects due to the oxidation process, which cannot be completely repaired during reduction, which seriously affects the electrical properties of graphene; epitaxial growth and chemical vapor deposition can be obtained. High-quality bulk graphene monoliths are currently the main means of preparing high-quality graphene

However, the preparation conditions of these two methods are harsh, the yield is not high, and the preparation cost is very high; Mix and heat to high temperature (200°C-700°C) and high pressure (10-100MPa), and then prepare graphene through cooling and depressurization process

The organic solvent used in this method is highly toxic, and the preparation process has high temperature (up to 700°C) and high pressure (up to 100MPa), and the steps are complicated, so it is not suitable for large-scale preparation of graphene.

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