Radioiodines ( 129 I and 131 I) are typical pollutants that accompany nuclear fission, which is a concern for environmental conditions and human metabolic processes. Therefore, it is important to find a sensitive detector to recognize harmful I 2 . Based on the above results, we further surveyed the sensitivity of JUC-557-nanosheet for I 2 . As shown from Fig. , the emission fluorescence intensity of JUC-557-nanosheet continuously decreased upon the gradual addition of I 2 , and the quenching percentage was nearly 100%.