Graphene and preparation method thereof

The invention relates to the field of functional materials, and discloses graphene and a preparation method thereof. The preparation method comprises the following steps: preparing a graphene aqueousdispersion with the content of 0.02-0.2wt%, and carrying out standing; under the same temperature, respectively measuring the absorbance of the same solvent dissolving solution with the same concentration of the graphene aqueous dispersion at the upper part, the middle part and the bottom of the same volume; after standing for 2 hours, the relative deviation of the absorbance of the dissolved solution of the graphene aqueous dispersion at the upper part, the middle part and the bottom part is not higher than 5%, preferably less than or equal to 1%; and after standing for 24 hours, the relativedeviation of the absorbance of the dissolved solution of the graphene aqueous dispersion at the upper part, the middle part and the bottom part is not higher than 10%, preferably less than or equal to 3%. The graphene provide