Self-co-reactant and ion-annihilation electrogenerated chemiluminescence of carbon nanodots

Abstract

Recently, the electrogenerated chemiluminescence (ECL) of carbon nanodots (C-dots) have been detected and the signal is applied for sensitive determination of environmental pollutes and biological active molecules. A few of researches have been reported on the mechanisms of C-dots that the electro-generated cation and anion intermediates undergo electron-transfer annihilation to give off strong ECL emission, which is quite similar to other nanoparticles. In this work, the ECL of C-dots through both co-reactant and annihilation pathways was examined by polarizing the working and counter electrodes in each isolated compartment of an H-shaped electrolytic cell. The peculiar self-co-reacted anodic ECL of C-dots was observed for the first time, to our best knowledge. The oxygen-containing groups especially the benzylic alcohol on the surface were proposed to turn into a strong reductant after losing one electron and one proton on anode, reducing the electrogenerated C-dots+ to exciting state C-dots* and causing the ECL emission. The ion-annihilation ECL under potential cycling and stepping was also observed which is mixed with co-reactant ECL. This work provided an insight into the distinctive structures of C-dots and the corresponding luminescent peculiarity.