▎ 摘　　要

NOVELTY - Preparation of sulfur-nitrogen co-doped graphene quantum dot solution comprises using citirc acid as carbon source, sodium heparin as sulfur source and protamine sulfate as nitrogen source, preparing into aqueous solution, and adjusting pH value with isopropanol. USE - The method is for preparing sulfur-nitrogen co-doped graphene quantum dot solution used as electrolyte for supercapacitor (claimed). ADVANTAGE - The electrolyte prepared has good cycle stability in electrochemical test, and broadens the application of graphene quantum dots in the field of electrochemistry. The method is green and environment friendly, and has simple equipment and experimental steps.