▎ 摘　　要

Heteroatom doped graphene quantum dots (GQDs) are particularly promising in bioimaging and fluorescent sensing because of their better photoluminescence tunability compared to pristine GQDs. Herein, two nitrogen and sulfur co-doped GQDs (N,S-GQDs) with varied fluorescence emission wavelength were synthesized via HNO3 vapour cutting route, in which a porous polythiophene-derived carbon served as the sulfur source while the HNO3 vapour was presented as the scissor and the nitrogen source. The as-prepared N, S-GQDs exhibited blue and yellow-green coloured fluorescence, owing to their varied morphologies and surface states resulted from varied reaction temperature. Compared to the typical top-down syntheses via hydrothermal or solvothermal routes, the present HNO3 vapour cutting method is prominently efficient in time expense and product separation. An application of the obtained greenish-yellow N,S-GQDs for highly selective and sensitive fluorescent detection of Fe3+ was demonstrated, with a linear range of 0-130 mu M and a detection limit of 0.07 mu M. The protocol reported here can also be readily applied for facial synthesis of other heteroatom doped GQDs.