Rational preparation of anti-water phosphorescent carbon-dots and flake C3N4 composites through microwave-heating method for multiple data encryption

The development of anti-water phosphorescent carbon dots (CDs) based materials is of great practical interest. Herein, we report a rational design of CDs based composite with anti-water phosphorescence by controlling a one-step microwave assisted heating of green fluorescent CDs and urea. Upon increasing the microwave-heating temperature, urea was gradually converted to C 3 N 4 , in which the CDs were uniformly embedded in the C 3 N 4 matrix. The fluorescence/phosphorescence intensity of these CDs based composites are determined by the morphologies of the C 3 N 4 , which can be adjusted by controlling the microwave heating time. More importantly, the combining CDs in C 3 N 4 not only promote the phosphorescence emission but also prevent the phosphorescence quenching by water, leading to stable phosphorescence emission in aqueous environment. Based on the anti-water phosphorescence properties of these CDs based composites, a concept of multiple data encryption was demonstrated.