▎ 摘　　要

NOVELTY - Preparing nitrogen-doped graphene quantum dot comprises taking nitrilotriacetic acid as raw material, reacting at high temperature and pressure, and then polymerizing to obtain nitrogen-doped graphene quantum dot. USE - The quantum dot is useful as fluorescent ink in ball-point pens in the form of oil (all claimed). ADVANTAGE - The quantum dot has uniform size, excellent dispersibility, high fluorescence yield, high purity and high yield. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for use of nitrogen-doped graphene quantum dot as fluorescent ink in ball-point pens in the form of oil comprising reacting oily fluorescent ink with nitrogen-doped graphene quantum dots saturated ethanol solution as main body, and mixing glycerol to obtain oily fluorescent ink, where volume ratio between ethanol and glycerol is 1:1-2:1.