Europium (III)‐modified sunflower‐derived carbon dots for fluorescent anti‐counterfeiting inks and photocatalysis

Abstract A highly water‐soluble and fluorescent N,S‐doped carbon dots/europium (N,S‐CDs/Eu) was successfully synthesized via a secondary hydrothermal method. This involved surface modification of N,S‐CDs derived from sunflower stem pith (SSP) with europium ions (Eu 3+ ) doping. When excited within the range of 400–470 nm, N,S‐CDs/Eu exhibited a stable and broad optimal emission wavelength ranging from 505 to 540 nm. Notably, the photoluminescence quantum yield (PLQY) of N,S‐CDs/Eu is 31.4%, significantly higher than the 19.5% observed for N,S‐CDs. Additionally, by dissolving N,S‐CDs/Eu into polyvinyl alcohol (PVA), a uniform fluorescent anti‐counterfeiting ink can be prepared. The N,S‐CDs/Eu/TiO 2 composite demonstrates excellent photocatalytic degradation ability towards the organic dye methylene blue (MB). N,S‐CDs/Eu has potential in the field of fluorescent inks and photocatalysis due to its simple and efficient preparation and excellent properties.