Dual-Emission\nAfterglow of Carbon Dots Induced by\nan Inorganic Salt for Anticounterfeiting and Temperature Sensing

Afterglow carbon dots (CDs) have been extensively studied\nfor sensing\nand anticounterfeiting because they can effectively block out the\ninterference of background light. In this work, m-APBA CDs are obtained\nhydrothermally with m-aminophenylboric acid (m-APBA) and different\nkinds of inorganic salts (IS). When m-APBA CDs are combined with CaCl<sub>2</sub> and MgCl<sub>2</sub>, dual-emission afterglow can be achieved\nbased on CaCl<sub>2</sub> and MgCl<sub>2</sub> having the strongest\naggregation ability, high charge density, structural confinement,\nand defects with respect to m-APBA CDs. The as-obtained CDs@CaCl<sub>2</sub> exhibits a dual mode afterglow with a quantum yield of 4.81%\nand lifetimes of 352 ms (delayed fluorescence) and 205 ms (phosphorescence).\nThe afterglow of CDs@IS can be excited by both UV and visible light\nat the same time, which could be recorded for about 8 ​​​and\n4 s. This unique method of inducing the m-APBA CD afterglow has the\nadvantages of simple synthesis, low cost, and adjustable afterglow\nemission. Moreover, CDs@IS showed exceptional performance in anticounterfeiting\nand temperature sensing, further establishing its practical utility.