Multi-confinement structured carbon dots with long room temperature phosphorescence lifetime and efficiency for sensing thiram residues assisted by copper ions.

Room temperature phosphorescent carbon dots (CDs@SiO) were obtained by encapsulating hydrothermally synthesized CDs in a dense Si-O network structure after high-temperature calcination using silica as the matrix. This can avoid the quenching effect of dissolved oxygen in water and has a phosphorescence lifetime of up to 2.41 s. Using the phosphorescence property of CDs@SiO, a phosphorescence quenching sensor was developed for the sensitive and selective detection of thiram with the assistance of Cu. Cu-thiram complexes led to a rapid phosphorescence quenching of CDs@SiO within 30 s through the inner filter effect. The linear range of phosphorescence for thiram was 0.5-100 µM with a detection limit of 0.121 µM. The proposed method was able to detect thiram in real samples and was validated by high-performance liquid chromatography (HPLC) confirming the potential of this phosphorescence sensing method for thiram detection. This work opens up a new avenue for the detection of thiram residues in fruits and vegetables and also provides a new idea for the design of a rapid detection platform using other room temperature phosphorescent materials.