▎ 摘　　要

Nitrogen doped graphene quantum dots (N-GQDs) have attracted much attention because of their superior electronic and optical properties. The preparation of N-GQDs can be usually performed via a top-down method using vairous nanocarbon as raw materials. However, most carbon materials are powder, which increases the difficulty of separating quantum dots from the reaction solution. Herein, we verified a feasibility of N-GQDs preparation with a bulk carbon film composed of N-doped carbon nanofibers as raw mateial via an acid vapor cutting approach (only 1 ml nitric acid was used in the method). The synthesis method effectively voids a tedious separation process. And the as-prepared N-GQDs exhibit good dispersion, high photostability and blue-green fluorescence. Subsequently, fluorescence experiments confirmed the fluorescence of N-GQDs was quenched selectively by Fe(3+)via the unique coordination interaction between them and recovered with the addition of AA. Based on the quenching (off) and recovering (on) processes, fluorescent sensor for Fe(3+)and OFF-ON fluorescent sensor for AA were fabricated, showing good selectivity and wide linear range. Finally, the constructed sensors were successfully applied for Fe(3+)and AA detection in real samples such as tap water and human urine.