"At that time, we did not realize it was graphene, and there was no concept of graphene." Jianhong Liu somewhat regrettably told "Da Guo Zhi Zhi" that the single-layer graphite prepared by the team in the laboratory 20 years ago turned out to be graphene, not realizing that it would have a series of excellent physics properties.

After seeing Dreyer Heim's paper being reported, Jianhong Liu realized that the monolayer graphite synthesized by his team was graphene and began to systematically explore its synthesis process, structural characterization by transmission electron microscopy, scanning electron microscopy, X diffraction, and Raman spectroscopy, as well as attempts to modify its structure and applications.

Unlike Nobel laureate André Heim's transparent glue repeatedly para-adhesive method and the mainstream CVD chemical vapor deposition method, redox method and other preparation paths, Jianhong Liu's team uses liquid-phase oligomers to synthesize graphene.

Jianhong Liu told "Da Guo Zhi Zhi" that chemical vapor deposition is to use natural gas as the carbon source, hydrocarbon cracking at about 1200 degrees Celsius, carbon deposited onto the copper foil, thus catalyzing the graphene structure, and then the structure is transferred out to prepare a graphene film. However, Jianhong Liu believes that this structure may contain non-graphene carbon structures such as amorphous carbon.

The other is graphene oxide reduction, which uses concentrated sulfuric acid and potassium permanganate as strong oxidants to oxidize on the graphite surface. However, the strong oxidizing agent will destroy the conjugate structure of graphite, which is a structure with alternating single and double bonds between carbon and carbon atoms. After the oxidation is completed to get graphene oxide dispersion, *** the process of reducing it is very complicated. "Once the co-structure has been destroyed, it is difficult to restore it back intact."

"The synthesis of single-atomic layer graphene by liquid-phase oligomer method is an original path for us." Jianhong Liu told The Big Country Material that only the intrinsic equation can produce single-layer graphene by this method, and only products based on single-layer or two-layer graphene can truly reflect the various advantages of graphene.

The liquid phase oligomer undergoes a gradual thermochemical reaction to transform from a linear molecule to a trapezoidal molecule and then to a planar molecule, *** which is carbonized, a process that makes the graphene structure very complete, and from the structure of the Raman spectrum, the graphene content of the single atomic layer obtained is as high as 97%.