▎ 摘　　要

NOVELTY - Preparing negatively charged graphene involves dispersing graphite in water and exfoliating graphite by mechanically by centrifugation to obtain single layer graphene. The carbon and oxygen ratio of graphene is 1.2-1.8:1. USE - Method for preparing negatively charged single layer graphene (claimed). ADVANTAGE - The method enables to prepare negatively charged single layer graphene in a simple and cost effective manner. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing graphene quantum dots which involves: (A) adding 1,3,6-trinitro-pyrene as a carbon source to 0.25-0.1 mol/L of aqueous alkaline solution; (B) heating hydrothermally in autoclave at 180-200 degrees C for 4-8 hours to synthetic graphene quantum dot; and (C) purifying by freeze-drying to obtain graphene quantum dot solid.