Fig. 12. (a) Synthesis of CQDs from urea and phenylenediamine. (b) Fluorescence of the CQDs under excitation at 365 nm. (c) The emission spectrum of the synthesized CQDs, and (d) the variation in the bandgap of the CQDs (no change in size) with the degree of surface oxidation (this figure has been adapted/reproduced from ref. 26 with permission from the American Chemical Society, Copyright 2015).
