ABSTRACT We report fluorescent carbon dots (CDs) functionalized with 4‐methylimidazole (4‐MI) synthesized via a one‐step hydrothermal method. Upon binding to toxic heavy metal ions, Hg 2+ and Cd 2+ , the fluorescence emission displayed a notable enhancement. This behavior contrasts with the majority of previously reported one‐step synthesized fluorescent CDs for metal ion sensing, which typically exhibit fluorescence quenching due to the nonradiative energy transfer. In this study, the 4‐MI functional group on the carbon nanoparticles prevents the nonradiative energy transfer when the analytes bind to the nanoparticle. Fluorescence responses were further examined by selectively removing and subsequently reintroducing the 4‐MI functional groups, demonstrating their critical role in fluorescence enhancement. These findings suggest considerable potential for developing CD‐based fluorescent enhancement sensing platforms for effective detection of heavy metal contaminants.
Kim et al. (2026) studied this question.