▎ 摘　　要

NOVELTY - Carboxylated graphene is prepared by ultrasonically dispersing graphene oxide in distilled water and grinding; adding resulting graphene oxide suspension with reducing agent hydrazine hydrate in oil bath of 85-95 degrees C and refluxing for 24-48 hours to obtain graphene oxide turbid liquid; adding the turbid liquid with alcohol solution of phenyl acid and isoamyl nitrite, adding strong alkali in oil bath of 70-80 degrees C and refluxing for 24-48 hours to obtain carboxylated graphene liquid precursor; and filtering liquid precursor, adding obtained solid with deionized water, and freeze-drying. USE - Method of preparing carboxylated graphene (claimed). ADVANTAGE - The method involves simple steps and avoids graphene agglomeration in solvent. The prepared carboxylated graphene is high purity fluffy powder and has good dispersibility. DETAILED DESCRIPTION - Preparation of carboxylated graphene comprises: (A) ultrasonically dispersing graphene oxide in distilled water at ultrasonic power of 600-900 W for 30-60 minutes and grinding to obtain 3 g/L uniformly dispersed graphene oxide suspension; (B) adding graphene oxide suspension with reducing agent hydrazine hydrate at ratio of 1:1-2 in oil bath of 85-95 degrees C and condensing and refluxing for 24-48 hours to obtain graphene oxide turbid liquid; (C) cooling the turbid liquid to 70-80 degrees C, adding alcohol solution of phenyl acid and isoamyl nitrite, then adding strong alkali (potassium hydroxide or sodium hydroxide) in oil bath of 70-80 degrees C and condensing and refluxing for 24-48 hours to obtain carboxylated graphene turbid liquid precursor, where the phenyl acid is phenylmethanoic acid or phenylacetic acid, and the alcohol is methyl alcohol or ethyl alcohol; (D) adjusting pH value of the liquid precursor to 5-6 using strong acid (hydrochloric acid or sulfuric acid); (E) filtering the liquid precursor, washing obtained solid substance with deionized water, adjusting pH value to 6-7, and filtering to obtain aqueous carboxylated graphene; and (F) gradually freeze-drying the aqueous carboxylated graphene for 5-7 days from 40 degrees C to 20 degrees C to obtain graphene powder.