(a) Schematic representation of activation of the afterglow luminescence of CDs through hydrogen bonding. (b) Small molecules used to construct hydrogen bonding for activating the afterglow luminescence of CDs. (c) Schematic illustration of the formation of hydrogen bonding network between CDs and melamine to activate the afterglow luminescence of CDs. (d) Photographs of CDs@melamine powder under UV on and off states with time (adapted and copyright permission [49
] (c, d), American Chemical Society). (e) Schematic illustration of the interactions among the CDs, CA particles, and water molecules. (f) Photograph (left) of the CD@CA suspension upon turn-off of UV light and the corresponding fluorescence image (right). Note that the fluorescence image was obtained by confocal laser scanning microscopy. The inset shows the size distribution of CD@CA obtained via dynamic light scattering (adapted and copyright permission [29
] (e, f), Nature Publishing Group).