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

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 K2S2O8. 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.