Research / 2021 / Article / Fig 6

Review Article

Afterglow Carbon Dots: From Fundamentals to Applications

Figure 6

(a) Schematic representation of activation of the afterglow luminescence of CDs via zeolite encapsulation. In this strategy, organic species in the synthesis of zeolite, such as solvent and structure-directing agent, were first carbonized into CDs which were then encapsulated with the in situ formed zeolite matrices at high temperatures. (b, c) SEM and TEM images of CDs@AlPO-5 composites. Inset in (b): the structures of the inorganic framework and SDA. Inset in (c): HRTEM of a selected CD showing crystal lattices. (d) The profile comparison of prompt (deep blue line) and delayed photoluminescence (blue line) of CDs@AlPO-5 under excitation at 370 nm. Inset: photographs of CDs@AlPO-5 under daylight, UV on, and UV off states. (e) The decay curve of the DF of CDs@AlPO-5 at 430 nm. Inset: schematic illustration of the interaction between the terminal –OH groups of the interrupted zeolite framework and the functional groups on the surface of the CDs (adapted and copyright permission [28] (a–e), American Association for Advancement of Science). (f) Schematic energy level diagrams presenting the energy transfer of the phosphorescence of CDs to the Mn2+ ions in the zeolite matrix of MnAPO-CJ50. Inset: the dependence of the luminescence of Mn2+ ions on their coordination configuration. (f) Prompt (black line) and delayed (red line) photoluminescence profiles of the CDs@MnAPO-CJ50 under excitation at 360 nm. Inset: photographs of the CDs@MnAPO-CJ50 under UV excitation and ceasing the excitation with different delay time (adapted and copyright permission [82] (f, g), Wiley-VCH Verlag GmbH & Co. KGaA).