▎ 摘　　要

NOVELTY - Preparing graphene quantum dot comprises mixing the carbon source material and nitric acid solution, heating at 110-150 degrees C for 10-14 hours to obtain suspension, performing the suspension centrifugal separation, leaving the first supernatant, adding de-ionized water and ammonia water into the supernatant to obtain the dispersion, placing dispersion into 160-200 degrees C environment, reacting for 8-12 hours to obtain the reaction liquid, performing the reaction liquid centrifugal separation, taking the second supernatant, performing film filtering to obtain filtrate, and drying. USE - The graphene quantum dot is useful for detecting ferric ions in water (claimed). ADVANTAGE - The method is simple, and is suitable for different carbon source. The graphene quantum dot has high fluorescence intensity, has a good sensitivity, reliability, repeatability, stability and anti-interference performance. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for graphene quantum dot prepared according to above mentioned method.