▎ 摘　　要

NOVELTY - A carbon material is dispersed in an ice bath in sulfuric acid, and potassium permanganate is added and stirred. After reaction completion, hydrogen peroxide is added to obtain a pale yellow transparent solution. The solution is pH-adjusted to neutral and filtered using a microporous membrane filter to obtain a clear pale yellow solution. The solution is dialyzed and water is evaporated to obtain green fluorescent graphene oxide quantum dots. The quantum dots are reduced or annealed at high temperature, to obtain blue fluorescent graphene quantum dots. USE - Preparation of graphene quantum dots for use in supercapacitors, lithium batteries, bio-imaging applications, solar batteries, FETs, and organic LEDs. ADVANTAGE - The method enables simple preparation of graphene quantum dots using easily available raw materials. The obtained quantum dots have excellent monodispersity and water solubility, and strong fluorescence. DETAILED DESCRIPTION - A carbon material is dispersed in an ice bath in sulfuric acid, and potassium permanganate is added and stirred. After reaction completion, a small amount of hydrogen peroxide is added with respect to excess potassium permanganate to obtain a pale yellow transparent solution. The solution is added with sodium hydroxide solution and pH is adjusted to 7-8, and then pH is set to neutral by addition of small amount of dilute hydrochloric acid solution. The obtained solution is filtered using a microporous membrane filter to obtain a clear pale yellow solution. The solution is dialyzed and water is evaporated to obtain green fluorescent graphene oxide quantum dots. The quantum dots are reduced or annealed at high temperature, to obtain blue fluorescent graphene quantum dots.