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

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 (Eu3+) 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/TiO2 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. A novel topic on the preparation of N,S-doped carbon dots/europium (N,S-CDs/Eu) from sunflower stem pith is proposed. The introduction of europium ions effectively increased the quantum yield of N,S-CDs from 19.5% to 31.4% of N,S-CDs/Eu. By mixing N,S-CDs/Eu with PVP as a fluorescent ink for anti-counterfeiting patterns, a means of encrypting information was developed. The degradation efficiency of N,S-CDs/Eu/TiO2 as a photocatalyst for MB dye can reach 93%. image