Green and sustainable synthesis of fluorescent carbon dots from crown daisy for information encryption application

•Synthesized green fluorescent carbon dots (G-CDs) from crown daisy and o-phenylenediamine via hydrothermal method.•G-CDs exhibit maximum excitation at 436 nm, emission at 539 nm, and quantum yield of 14.5 % in ethanol.•Demonstrated G-CDs' excellent salt tolerance, pH stability, and photostability, with excitation-independent emission.•Applied G-CDs as anti-counterfeiting ink, creating a clear QR code under UV light for information encryption. Herein, we report a sustainable and eco-friendly synthesis of green fluorescent carbon dots (G-CDs) from crown daisy, a common vegetable, and o-phenylenediamine via a hydrothermal method. The synthesized G-CDs were comprehensively characterized using various spectroscopic techniques, revealing a maximum excitation wavelength of 436 nm and emission at 539 nm with a quantum yield of up to 14.5 % in ethanol. The optical properties was systematically investigated, demonstrating the excellent salt tolerance, pH stability, and photostability of the G-CDs. Notably, the G-CDs exhibited excitation-independent emissions behavior, indicating a single type of fluorescent emission center. The practical application of G-CDs as anti-counterfeiting ink was demonstrated by generating a clear QR code pattern under UV illumination, showcasing their potential for information encryption and anti-counterfeiting applications. This work not only provides a sustainable and cost-effective approach for G-CD synthesis but also highlights their promising prospects in optical anti-counterfeiting and information encryption domains.