The preparation was based on a rapid, eco-friendly and efficient acid vapor cutting strategy, which was different from previously reported solution chemistry routes. The as-prepared N-GQD was photoluminescent. The fluorescence peak of the N-GQDs remained at around 490 nm when the excitation wavelength changed from 290 nm to 410 nm, exhibiting an excitation-independent behavior. The research demonstrated that the MOF-derived carbon can be used as a starting material for synthesis of nitrogen-doped graphene quantum dots.

The obtained N-GQDs serve as a fluorescent sensing probe for the detection of ferric ions with both excellent selectivity and a low detection limit of 80 nM (S/N=3). The effects of the potential interfering ions (Ag⁺, Al³⁺, Ca²⁺, Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Hg²⁺, K⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺ and Na⁺) on the relative fluorescence intensity of the N-GQDs towards Fe³⁺ were examined at an excitation wavelength of 330 nm. This interference study proved that the N-GQD is highly selective for Fe³⁺ in aqueous solution. This work would enable new opportunity for the wider use of MOFs-based material and also contributes to the fluorescent analysis of Fe³⁺.