Nitrogen-Doped Carbon Quantum Dots with Photoactivation Properties for Ultraviolet Ray Detection

Abstract

Photoactivation is a phenomenon that could enhance the photoluminescence (PL) and photostability upon UV/vis light exposure, which is usually observed in CdSe/ZnS quantum dots (QDs). However, the photoactivation phenomenon has been scarcely reported in fluorescent carbon quantum dots (CQDs). Herein, the nitrogen-doped carbon quantum dots (N-CQDs) were prepared through a facile solvothermal approach with naphthalenetracarboxylic dianhydride and serine as precursors. Upon simple UV light irradiation for 10 min, the fluorescence quantum yield (QY) of N-CQDs could increase up to 10-fold. Based on this phenomenon, the N-CQDs were explored as an ultraviolet (UV) light sensor to assess the intensity of ultraviolet radiation in sunlight and indirectly evaluate the UVblocking efficiency of various sunscreen products. Thus, this contribution not only provided an insight into developing a low-cost UV detector but also opened a door for the development of carbon quantum dots with converse-photobleaching properties.