▎ 摘　　要

By doping heteroatoms (B, N, S, P and Si) into graphene quantum dots (GQDs), the surface and local chemical features of GQDs could be effectively improved and the optical characteristics be adjusted. Herein, a (B, N, S) co-doped BNS-GQDs was designed and synthesized for "OFF-ON-OFF" fluorescence detection to Fe3+ and H2PO4- in pure water. BNS-GQDs prepared by hydrothermal method had a uniform particle size with average diameter of 4 nm. TEM, XRD, Raman, FTIR and XPS analysis results showed that BNS-GQDs had a similar structure to graphene, and the heteroatoms (B, N, S) had been successfully doped into GQDs. The fluorescence spectra showed that the selective detection of Fe3+ was achieved based on fluorescence quenching of BNS-GQDs, and its fluorescence could be restored after the addition of H2PO4- that could be used to detect H2PO4- with high sensitivity. Meanwhile, the detection limits for Fe3+ and H2PO4- were 4.35 mu mol/L and 1.02 mu mol/L, respectively. The interaction mechanism between BNS-GQDs and ions was discussed by fluorescence attenuation test and TEM. It was suggested that the fluorescence quenching of BNS-GQDs caused by Fe3+ might be based on static quenching and/or excited state electron transfer. The introduction of H2PO4- destroys the interaction between BNS-GQDs and Fe3+. The recognition of BNS-GQDs for Fe3+ and H2PO4- had good reversibility. Also, BNS-GQDs was successfully applied to monitor concentration of Fe3+ and H2PO4- in Hela cells and real water samples by fluorescence response, suggesting its potential and significance in bioanalysis and environment detection in the future.