Revealing carbon nanodots as coreactants of the anodic electrochemiluminescence of Ru(bpy)₃²⁺.

Recently, research on carbon nanodots (C-dots), a new type of luminescent nanoparticles with superior optical properties, biocompatibility, and low cost, has been focused on exploring novel properties and structure-related mechanisms to extend their scope. Herein, electrochemiluminescence, a surface-sensitive tool, is used to probe the unrevealed property of carbon nanodots which is characterized by surface oxygen-containing groups. Together with chemiluminescence, carbon nanodots as the coreactants for the anodic electrochemiluminescence of Ru(bpy)3(2+) are demonstrated for the first time. During the anodic scan, the benzylic alcohol units on the C-dots surface are oxidized "homogeneously" by electrogenerated-Ru(bpy)3(3+) to form reductive radical intermediate, which further reduce Ru(bpy)3(3+) into Ru(bpy)3(2+)* that produces a strong ECL emission. This work has provided an insight into the ECL mechanism of the C-dots-involved system, which will be beneficial for in-depth understanding of some peculiar phenomena of C-dots, such as photocatalytic activity and redox properties. Moreover, because of the features of C-dots, the ECL system of Ru(bpy)3(2+)/C-dots is more promising in the bioanalysis.