Preparation, Properties, and Applications of Fluorescent Carbon Quantum Dots in Anticounterfeiting

With growing demand for information security and product authentication, the development of efficient, environmentally friendly anticounterfeiting materials has become an urgent priority. Fluorescent carbon quantum dots (CQDs), an emerging class of nanomaterials, exhibit remarkable potential for this purpose owing to their excellent optical tunability, low toxicity, and abundance of carbon-based precursors. This review summarizes recent advances in the synthesis, functionalization, and application of fluorescent CQDs for anticounterfeiting technologies. It first outlines key synthesis strategies, broadly classified into top-down and bottom-up approaches, and discusses how functionalization enables tunable dispersion, stability, biocompatibility, and optical responses suited to specific security applications. Second, the anticounterfeiting applications of CQDs are highlighted, including fluorescence-based anticounterfeiting such as invisible fluorescent inks, anticounterfeiting composite films, stimulus-responsive smart encryption-decryption tags, and information-encoding invisible coatings, as well as phosphorescence-based anticounterfeiting focusing on the construction of multilevel data encryption and time-dependent dynamic response encryption systems. Finally, the challenges confronting CQDs in the development of sustainable anticounterfeiting systems are discussed, and key breakthroughs are required in industrial-scale production, optical stability enhancement, and integrated applications with artificial intelligence.