A novel method for the detection of silver ions with carbon dots: Excellent selectivity, fast response, low detection limit and good applicability

With the extensive application of silver containing materials in industry, the issue of release of silver ions has attracted increasing attention due to toxic effect of silver ions on the human health and environment. Traditionally, silver ions can be detected by atomic absorption spectroscopy, atomic emission spectrometry etc., which needed expensive and elaborate instruments and were high energy consumption. Therefore, economic and convenient methods are required for the effective determination of silver ions. Herein, two types of carbon dots (CDs-1 and CDs-2) have been prepared through a solvothermal synthesis method by using sucrose or citric acid and tris(hydroxymethyl)aminomethane as precursor, respectively. Then, CDs-1 were developed for the detection of silver ions through a colorimetric method. The detection mechanism was based on the reduction of silver ions and the formation of silver nanoparticles, which possess unique surface plasma resonance properties. CDs-1 could both act as reductants and stabilizers during the reaction for determination of silver ions. This CDs-1 based detection system could quantitatively determine silver ions in 3 min with a limit of detection (LOD) of 26 nmol/L (2.81 ppb). Interestingly, this strategy could also realize the detection of silver ions by CDs-2. Furthermore, the sensing assay is applicable to detecting silver ions in lake water and silver sulfadiazine cream samples.