Electrogenerated Chemiluminescence Emissions from CdS Nanoparticles for Probing of Surface Oxidation

Electrogenerated chemiluminescence (ECL) of nanoparticles are known to be strongly dependent on the surface states, whereas the detailed mechanisms are not clear. Here, the detailed ECL mechanisms of CdS nanopaticles have been investigated. It was found that ECL emission observed at −0.95 V (600 nm, 700 nm) is assigned to the reduction of the surface S vacancy, whereas the luminescence at −1.25 V (520 nm) is attributed to the electron injection to the conduction band in the cathodic process. On the basis of these mechanisms, for the first time, we are able to observe the gradual ECL evolution of CdS nanoparticles in the presence of oxidant, therefore online monitoring the surface oxidation of CdS nanoparticles by the ECL method. This method will find more application in surface probing of nanomaterials because the ECL of nanomaterials is very sensitive to the surface.