The synthesis of Ag@CQDs composite and its electrochemiluminescence application for the highly selective and sensitive detection of chloride

Abstract Carbon quantum dots (CQDs) decorated Ag nanoparticles (Ag@CQDs) were successfully synthesized and characterized by UV-Vis spectroscopy, fluorescence, FT-IR, and transmission electron microscopy (TEM), then utilized for the sensitive detection of chloride ions (Cl − ). Compared to CQDs, the Ag@CQDs showed stronger electrochemiluminescence (ECL) in 0.1 M PBS (pH = 7.4) containing 0.1 M K 2 S 2 O 8 . In the presence of chloride (Cl − ), a significant reduction in the ECL intensity of Ag@CQDs was noticed, which was used to develop a sensitive detection method of Cl − . The ECL quenching of Ag@CQDs was utilized to establish the method, of which the mechanism might be caused by the formation of AgCl on the Ag@CQDs composite surface. The prepared Cl − sensor showed a wide linear range (0.99–450 nM) and low detection limit (0.33 nM). Furthermore, the prepared sensor exhibited high sensitivity and good selectivity towards several ion inferences.