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 x 10(-7) mol L-1) of ECL is lower than that (1.0 x 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 x 10(-7) and 1.0 x 10(-5) mol L-1 with a detection limit of 6.0 x 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. (c) 2007 Elsevier B.V. All rights reserved.