▎ 摘　　要

NOVELTY - Preparing graphene comprises (i) taking graphite powder and alkyl sulfonic acid solution, and mixing under magnetic force to obtain graphite-alkyl sulfonic acid dispersion liquid, (ii) continuously stirring under magnetic force, dropping hydrogen peroxide solution into the dispersion liquid, and stopping magnetic force stirring process, (iii) subjecting the dispersion liquid to ultrasonic wave treatment, (iv) centrifuging the resulting liquid, using deionized water for repeatedly washing until the completely removing sulfate, and (v) drying the washed dispersion liquid under vacuum condition. USE - The graphene is useful as microelectronics, optical, magnetic, biomedical, catalysis, energy storage, sensor material and multifunctional composite material. DETAILED DESCRIPTION - Preparing graphene comprises (i) taking graphite powder and alkyl sulfonic acid solution according to mass (g) volume (ml) ratio of 1:100-150, mixing under magnetic force, and stirring to obtain graphite-alkyl sulfonic acid dispersion liquid, where the graphite powder is natural crystalline flake graphite powder (graphite content is greater than or equal to 99%), and the alkyl sulfonic acid (purity is greater than or equal to 96%) is methanesulfonic acid or ethyl sulfonic acid, (ii) continuously stirring under magnetic force, dropping 30 wt.% hydrogen peroxide solution (impurity content is less than or equal to 0.005%) under dropping rate of 2 ml/minute into the dispersion liquid, the total volume of hydrogen peroxide dropped in the graphite-alkyl sulfonic acid dispersion liquid is 50-75 vol.%, after completing dropping, maintaining for 5-10 minutes, and stopping magnetic force stirring process, (iii) subjecting the dispersion liquid to ultrasonic wave treatment under ultrasonic wave power of 280-420 W for 30-60 minutes, (iv) centrifuging the resulting liquid, using deionized water for repeatedly washing until the completely removing sulfate (using 0.25 mol/l barium calcium chloride solution for detecting), and (v) drying the washed dispersion liquid under vacuum condition at 60 degrees C for 10-24 hours to obtain graphene solid powder.