Environment‐Sensitive Carbon Dots Derived from Naphthalenediol for Solvent Polarity Indicator and Anti‐Counterfeiting

Abstract Herein, a novel type of environment‐sensitive carbon dots (ES‐CDs) has been synthesized via ethanothermal reaction using 1,6‐naphthalenediol as a carbon source and sulfuric acid as a catalyst. The morphology and structure of ES‐CDs are characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectra (XPS). ES‐CDs exhibit green and excitation wavelength independent emission in different solvents. Using the optical response of ES‐CDs towards acetone‐water binary mixtures with different composition, the sensitive detection of solvent polarity is realized based on the inner filter effect (IFE). The ink‐jet printed patterns of ES‐CDs show a blue‐to‐green conversion as exposure to external vapor from hydrogen chloride to ammonia, and enable information to hide assisting with a laser direct writing. We believe that the environment‐sensitive carbon dots developed in this study are potential candidates for solvent sensing and fluorescence anti‐counterfeiting.