Dramatic photoluminescence quenching in carbon dots induced by cyclic voltammetry

This study focuses on the structural rearrangements and the photoluminescent behavior of pyrolytically derived carbon dots when subjected to a series of cyclic voltammetry sweeps. Although the electrical signals involved are not pronounced, multiple electrochemical cycling results in a progressive suppression of the photoluminescence, so that after 42 sweeps the intensity is reduced by one order of magnitude. At the same time, the fluorescence component stemming from the organic fluorophores is blue-shifted, while the contribution of the carbogenic cores is red-shifted. XPS and FTIR spectra reveal that the voltammetric field induces an extensive formation of C-O and C&z.dbd;O at the expense of the C&z.dbd;C bonds. Our findings indicate a close relationship between the electrochemical response and the structure of C-dots and, thus, have direct implications on the development of C-dot based electroluminescent materials, electrochemical sensors and solar cells. We disclose an electrochemically activated quenching mechanism that is dominant in certain types of C-dots.