▎ 摘　　要

NOVELTY - Natural flake graphite and potassium permanganate are mixed, and mixed acid of concentrated sulfuric and phosphoric acid is added and reacted. Mixture is then placed in water bath, stirred and obtained graphite oxide solution is poured into distilled water containing hydrogen peroxide, and completely dissolved. Resultant solution is filtered, pickled, washed and dried to obtain graphite oxide. Graphite oxide is dissolved in acetic acid solution, and hydroiodic acid is added and stirred. Resultant solution is filtered, and obtained cake is washed and dried to obtain graphene. USE - Preparation of graphene (claimed). ADVANTAGE - The method efficiently provides high yield of graphene having high conductivity at low temperature with high productivity, by simple method without affecting the environment. DETAILED DESCRIPTION - Natural flake graphite and potassium permanganate are mixed in three-necked flask in the weight ratio of 1:4-6. A mixed acid of concentrated sulfuric and phosphoric acid is gradually added, and reacted by stirring for 30 minutes, such that the volume ratio of concentrated sulfuric acid and concentrated phosphoric acid is 9:1. The ratio of mixed acid and natural flake graphite is 120 ml:1 g. The three-necked flask is placed in water bath at 50 degrees C while stirring for 10 hours, to obtain graphite oxide solution. Distilled water and hydrogen peroxide are mixed in the volume ratio of 20:1, and frozen into ice. The obtained graphite oxide solution is poured into distilled water containing hydrogen peroxide, and completely dissolved. The resultant solution is filtered, pickled, washed and dried to obtain graphite oxide. The content of distilled water is 100-150 ml with respect to 1 g graphite. The concentration of hydrogen peroxide is 30 wt.%. The obtained graphite oxide is dissolved in 36-38 wt.% acetic acid solution, and 55 wt.% hydroiodic acid is added and stirred at 40 degrees C. The resultant solution is then filtered, and obtained cake is washed using water and alcohol. The resultant product is then dried to obtain graphene. The ratio of graphite oxide and acetic acid is 1 g:300-400 ml. The ratio of graphite oxide and hydrogen iodide is 1 g:10-40 ml.