Fluorescence spectroelectrochemistry for the study of electrochemiluminescence of the CdTe quantum...

This study investigates the electrochemiluminescence (ECL) behavior of water-soluble cadmium telluride quantum dots (CdTe QDs) synthesized via a microwave-assisted hydrothermal method. The ECL response was examined in the presence of tri-n-propylamine (TPrA) as a coreactant, revealing two anodic ECL emissions, denoted as ECL₁ and ECL₂, at potentials of + 0.85 V and + 1.2 V, corresponding to TPrA oxidation and CdTe QD oxidation, respectively. These emission intensities showed strong dependence on pH, suggesting multiple mechanistic pathways. In situ fluorescence microscopy was employed to observe interactions between electrogenerated TPrA intermediates and CdTe QDs at the electrode surface, providing insights into the reaction mechanisms. It is proposed that ECL₁ arises from reactions involving the TPrA^•+ intermediate under mildly basic conditions (pH 8-9), where both TPrA^•+ and TPrA^• radicals facilitate electron transfer with CdTe QDs, resulting in low-potential ECL emission. The findings demonstrate that TPrA^•+ acts as both a fluorescence quencher and a reactive intermediate, advancing understanding of the pH-dependent anodic ECL mechanism of semiconductor QDs.