▎ 摘　　要

NOVELTY - Preparing nitrogen-doped graphene quantum dot material involves preparing nitrogen-doped graphene quantum dots, which are N-graphene quantum dots (GQDs), and R-N-GQDs, freeze-drying and re-dispersing. The two nitrogen-doped graphene quantum dots are prepared by measuring a certain volume of N,N-dimethylformamide solution, performing reaction treatment on the N,N-dimethylformamide solution in an oil bath, and cooling down to obtain the N-GQDs solution, putting processed N-GQDs solution in a freeze dryer for a certain period of time to freeze and drying, dissolving the frozen and dried sample in a certain volume of N, N-dimethylformamide solution, and ultrasonically processing the dissolved sample for a certain period of time to obtain R-N-GQDs solution. USE - Method for preparing nitrogen-doped graphene quantum dot material that is utilized for detecting trace trivalent iron ions by fluorescence method (claimed). ADVANTAGE - The quantum dot material can achieve high-efficiency fluorescence detection of trace ferric ions in water, and low detection limits of 0.081-0.058 mu M, and can quickly detect trace trivalent iron ions in experimental samples and actual samples, and has a strong prospect for popularization and application, and high reliable re-monodisperse property, and can be prepared in simple and cost effective manner.