Electochemiluminescence of CdTe/CdS Quantum Dots with Triproprylamine as Coreactant in Aqueous Solution at a Lower Potential and Its Application for Highly Sensitive and Selective Detection of Cu2+

Anodic electrochemiluminescence (ECL) of 3-mercaptopropionic acid (MPA)- capped CdTe/CdS core-shell quantum dots (QDs) with tripropylamine (TPrA) as the co-reactant were studied in aqueous (Tris buffer) solution for the first time. The results suggest that the oxidation of TPrA at a glassy carbon electrode (GCE) surface participated in the ECL of QDs, and the onset potential and the intensity of ECL of CdTe/CdS QDs were affected seriously by TPrA, as the co-reactant, in Tris buffer solution. The onset potential of ECL in this new system was about +0.5 V (vs. Ag/AgCl) and the ECL intensity greatly enhanced when TPrA was present. Various influencing factors. such as the electrolyte, pH, QDs concentration, potential range and scan rates on the ECL were studied. Based on the selective quenching by Cu2+ to the light emission front CdTe/CdS QDs/TPrA system, a highly sensitive and selective method for the determination of Cu2+ was developed. At the optimal conditions, the relative ECL intensity, I-0/I was proportional to the concentration of Cu2+ from 14 nM to 0.2.1 mu M with the detection limit of 6.1 nM based on the signal-to-noise ratio of 3. The possible ECL mechanism of QDs and the quenching mechanism of ECL were proposed.