Sustainable fabrication of N-doped carbon quantum dots and their applications in fluorescent inks, Fe (III) detection and fluorescent films

Abstract

N-doped CQDs are efficiently fabricated with a green synthesis avenue, and exhibit huge potential in anticounterfeit application as the fluorescent ink, a smart fluorescent sensor towards ionic detection, and fluorescent polymer films. • One-step hydrothermal strategy is devised for synthesizing N-doped CQDs from garlic skins. • The obtained water-soluble N-doped CQDs exhibit a strong cyan luminescence with a quantum yield of ∼9%. • The CQDs present huge potential in anticounterfeit application as the fluorescent ink. • The CQDs show highly sensitive and selective determination of cations as a smart fluorescent sensor. • The PVA/CQDs film gives high visible transparency and nearly 100% UV-blocking ratio. In this work, the highly fluorescent N-doped carbon quantum dots (CQDs) were successfully synthesized via a simple hydrothermal method by using garlic skins (GSs) as the sole carbon source. The resultant N-doped CQDs with excitation-dependent emission demonstrates remarkable quantum yield of ∼9% and superior fluorescence stability. Their strong cyan-emission character upon irradiation with UV light (365 nm) reveals their huge potential in anticounterfeit field as the fluorescent ink. Owing to the fluorescence quenching resulted from the tightly chelating of Fe 3+ to the surface of N-doped CQDs, the CQDs can be applied a functional sensor for the detection of Fe 3+ , and the limit of detection is estimated as 4.44 μM. Furthermore, the CQDs is dispersed into poly (vinyl alcohol) (PVA) matrix to make PVA/CQDs composite film. The unique optical properties of CQDs are inherited by the PVA/CQDs film, giving intensive cyan fluorescence and high visible transparency, as well as nearly 100% UV-blocking ratio in the UV region.