Electrogenerated chemiluminescence from CdS nanotubes and its sensing application in aqueous solution

Electrogenerated chemiluminescence (ECL) of CdS nanotubes in aqueous solution and its sensing application were studied by entrapping the CdS nanotubes in carbon paste electrode. Two ECL peaks were observed at −0.9 V (ECL-1) and −1.2 V (ECL-2), respectively, when the potential was cycled between 0 and −1.6 V. The electrochemically reduced nanocrystal species of CdS nanotubes could collide with the oxidized species in an annihilation process to produce the peak of ECL-1. The electron-transfer reaction between the reduced CdS nanocrystal species and oxidant coreactants such as S2O82−, H2O2, and reduced dissolved oxygen led to the appearance of the ECL-2 peak. Based on the enhancing effect of H2O2 on ECL-2 intensity, a novel CdS ECL sensor was developed for H2O2 detection. The sensor exhibited a detection limit of 0.1 μM and a linear range from 0.5 μM to 0.01 mM. The relative standard deviations of five replicate determinations of 5 μM H2O2 was 2.6%. In addition, the ECL spectrum in aqueous solution also exhibited two peaks at 500 and 640 nm, respectively.