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About preparation method of graphene

wallpapers News 2021-08-12
Even in principle, isolated 2D crystals cannot be grown beyond small sizes by chemical synthesis, because the phonon density increases rapidly with the increase in lateral size, forcing the 2D crystallites to bend to the third dimension. In all cases, graphene must be bonded to the substrate to maintain its two-dimensional shape.
As of 2014, the graphene produced by exfoliation has the lowest number of defects and the highest electron mobility. A sharp single-crystal diamond wedge penetrates the graphite source to cleave the layers.
Using graphite as the raw material, the local shear rate generated by the mixer is greater than 10×104, and defect-free, non-oxidized graphene-containing liquid can be prepared.
Burning a DVD coated with graphite oxide produces a conductive graphene film (1738 S/m) with high resistance and ductility and a specific surface area (1520 m2/g).
Dispersing graphite in a liquid medium and then ultrasonic treatment and centrifugation can produce graphene with a production concentration of 2.1 mg/mL (in N-methyl pyrrolidone). Using a suitable ionic liquid as the dispersion liquid can produce a concentration of 5.33 mg/mL.
Molten salt
Graphite particles can be corroded in molten salt to form various carbon nanostructures including graphene. Hydrogen cations dissolved in molten lithium chloride can be placed on cathode-polarized graphite rods and then deintercalated to exfoliate graphene sheets. The graphene nano sheets produced showed a single crystal structure with a lateral size of several hundred nanometers, as well as a high degree of crystallinity and thermal stability.
Electrochemical synthesis
Electrochemical synthesis can exfoliate graphene. Change the pulse voltage to control the thickness, sheet area, number of defects and affect its performance. This process starts by immersing graphite in a solvent for intercalation. The process can be tracked by using light-emitting diodes and photodiodes to monitor the transparency of the solution.