N-doped carbon dots under Xenon lamp irradiation: Fluorescence red-shift and its potential mechanism.

Despite extensive research on carbon dots (CDs), rare studies have been performed on the photostability of CDs. Here, the photostability of CDs synthesized with 3-aminobenzoic acid were systematically investigated under different pH conditions (5.0, 7.4 and 9.0). The results showed that under Xenon lamp irradiation, the fluorescence (FL) intensity of the CDs exhibited an increase first and then a decrease, with a gradual shift of the maximum emission wavelength to longer wavelength. Further investigation indicated that the irradiation induced the change of the CD surface functional groups and gave rise to aggregation, resulting in the formation of larger particles. This study provided important reference value towards research on CDs properties.