Enhanced electrochemiluminescence behavior of C,N quantum dots embedded g-C₃N₄ nanosheets and its sensing application for copper (II)

Electrochemiluminescence (ECL) is a very sensitive method for trace analysis because of its background interference and high signal-to-noise ratio. In the past decade, the determination of Cu²⁺ in environment has attracted considerable attention since it plays an essential role in many physiological processes. Herein, a novel ECL sensor based on C,N quantum dots embedded g-C₃N₄ nanosheets (C,N-QDs@NSs) was constructed for the detection of Cu²⁺. The nanocomposite was rapidly obtained via the oxidation of normal g-C₃N₄ in H₂O₂ solution using sonochemical synthesizing method. Due to the abundant surface defects on C,N-QDs@NSs, the ECL intensity was magnified 2.5 times for using a C,N-QDs@NSs electrode in comparision to a g-C₃N₄ modified electrode. Besides, C,N-QDs@NSs could accelerate the rate of electron transfer in ECL reaction and thus resulted in the lower cathodic peak potential. Significantly, Cu²⁺ could effectively quench the ECL of C,N-QD@NSs, which endowed C,N-QD@NSs with a great advantage in the ECL detection of Cu²⁺. under optimum conditions, C,N-QDs@NSs modified electrode exhibited a linear detection range from 5 × 10⁻⁴ to 10 µM with a detection limit of 2 × 10⁻⁴ µM (S/N = 3) for Cu²⁺, and was finally applied to detect Cu²⁺ in real samples with satisfactory results.