Electrogenerated chemiluminescence from thiol-capped CdTe quantum dots and its sensing application in aqueous solution

In this paper, the electrogenerated chemiluminescence (ECL) from thiol-capped CdTe quantum dots (QDs) was reported. The ECL emission was occurred at −1.1 V and reached a maximum value at −2.4 V when the potential was cycled between 0.0 and −2.5 V. The reduced species of CdTe QDs could react with the coreactants to produce the ECL emission. The CdTe QD concentration (6.64 × 10−7 mol L−1) of ECL is lower than that (1.0 × 10−3 mol L−1) of chemiluminescence (CL). Based on the enhancement of light emission from thiol-capped CdTe QDs by H2O2 in the negative electrode potential, a novel method for the determination of H2O2 was developed. The light intensity was linearly proportional to the concentration of H2O2 between 2.0 × 10−7 and 1.0 × 10−5 mol L−1 with a detection limit of 6.0 × 10−8 mol L−1. Compared with most of previous reports, the proposed method has higher sensitivity for the determination of H2O2. In addition, the ECL spectrum of thiol-capped CdTe QDs exhibited a peak at around 620 nm, which was substantially red shifted from the photoluminescence (PL) spectrum, suggesting the surface states play an important role in this ECL process.