Research progress on functional carbon dots for detecting heavy metal ions in the fields of environmental protection and food safety.

Traditional heavy metal detection methods have limitations such as expensive equipment, complex operation, and difficulty in rapid on-site detection, which have made it difficult to meet the urgent needs of environmental protection and food safety for efficient, sensitive, and portable detection. Carbon dots (CDs), as an emerging fluorescent carbon nanomaterial, have excellent photostability, tunable fluorescence performance, low toxicity, and easy surface functionalization, showing great potential in heavy metal ion detection. This article systematically reviews various preparation methods of functional carbon dots, focusing on their fluorescence sensing mechanisms and performance optimization strategies for detecting heavy metal ions such as Hg, Pb, and Cu in the fields of environmental protection and food safety in the past five years. The future development direction is also discussed, in order to provide theoretical reference for the development of new methods for high sensitivity, high selectivity, and environmentally friendly heavy metal detection.