Fig. 1. PL spectra of the CDs prepared at diverse reaction conditions (the insert tables show the corresponding QYs of CDs)

Fig. 2. Spectroscopic characterization of B-CDs at optimal fluorescence

Fig. 3. Morphologic structure characterization of B-CDs at optimal fluorescence

Fig. 4. Fluorescence quenching effect of Fe³⁺ and Ag⁺ towards the CDs solution

Fig. 5. Fluorescence quenching mechanism of Ag⁺ towards the CDs solution

Fig. 6. Fluorescence quenching mechanism of Fe³⁺ towards the CDs solution