▎ 摘　　要

NOVELTY - Preparing graphene comprises (a) crushing graphite particles using a ball mill, (b) adding hydrochloric acid solution to crushed product and then stirring to remove impurities, (c) rinsing stirred product with deionized water until the pH value of the mixture reaches neutral, (d) drying obtained mixture, (e) adding nitric acid solution to dried mixture and then stirring, (f) adding potassium permanganate to mixture and then heating, (g) filtering hot mixture and then adjusting pH value, and (h) drying filtered mixture to obtain intercalated graphite oxide. USE - The method is useful for preparing graphene (claimed). ADVANTAGE - The method is capable of easily and economically preparing graphene with controlled thickness, improved productivity and stability, and reduced defects. DETAILED DESCRIPTION - Preparing graphene comprises (a) crushing graphite particles having a particle size of 50-100 meshes for 0.5-2 hours using a ball mill, (b) adding 10-38 wt.% of hydrochloric acid solution to the crushed product and then stirring for 1-20 minutes to remove impurities, (c) rinsing the stirred product with deionized water until the pH value of the mixture reaches neutral, (d) drying the obtained mixture, (e) adding 48-68 wt.% of nitric acid solution to the dried mixture and then stirring for 15-30 minutes, (f) adding potassium permanganate to the mixture and then heating at 10-20 degrees C for 60-90 minutes, (g) filtering the hot mixture and then adjusting pH value to 6-7, (h) drying the filtered mixture to obtain intercalated graphite oxide, (i) adding nitrate solution to intercalated graphite oxide at a ratio of 1g:3-5 ml, (j) heat-treating the intercalated graphite oxide for 1100-1200 degrees C for 80-100 seconds in a muffle furnace to obtain expanded graphite, (k) adding more than 98% of concentrated sulfuric acid to the expanded graphite at a ratio of 1 g: 35-45 ml and then stirring for 30-60 minutes, (l) adding potassium permanganate to the mixture at a ratio of 1:5-7 and then stirring at a speed rate of 1-5 revolutions per minute, (m) cooling the mixture at -5 degrees C to 0 degrees C for 10-140 minutes to obtain a reaction solution, (n) transferring the reaction solution into a reaction kettle, (o) adding deionized water to the kettle at a ratio of 40-60 ml:1 g and then heating at 100-105 degrees C for 1 minute to 20 minutes, (p) drop-wisely adding 20-30% of hydrogen peroxide to the solution in the kettle in a ratio of 18-22 ml:1 g to obtain golden yellow solution, (q) drop-wisely adding aqueous ammonia to the golden yellow solution, (r) adjusting pH value of the mixture to 8-9 and then heating at 40-50 degrees C, (s) filtering the mixture to obtain a solid material, rinsing the solid material with deionized water and then drying at 30-40 degrees C for 8-24 hours, (t) dissolving the dried product in an organic solvent and then stirring for 30-50 minutes and adding liquid nitrogen to the solution, (u) allowing the solution to stand for 20-40 minutes, (v) heating the solution at 60-95 degrees C for 1-3 hours and then washing with deionized water and filtering and (w) drying and (x) adding hydrazine hydrate to the dried product at a mass ratio of 0.8-1.5 ml:1 g to obtain graphene.