Activating aqueous room temperature phosphorescence in N, S, B co-doped carbon dots for Fe³⁺ detection and...

Carbon dots (CDs) exhibiting room temperature phosphorescence (RTP) have drawn significant research attention due to their wide-ranging potential applications. However, achieving long-lived phosphorescence in aqueous solutions remains challenging owing to quenching effects induced by dissolved oxygen. In this study, a novel RTP CDs was developed through heteroatom doping strategy using folic acid, thiourea, and boric acid as precursors. Notably, cyanuric acid (CA) was used as a matrix to encapsulate the synthesized CDs, promoting a compact structure and activating their phosphorescence in aqueous solution. The N, S, B-CDs@CA composite demonstrated green RTP, achieving a phosphorescence quantum yield of 29.55% and a lifetime of 614 ms. In addition, N, S, B-CDs@CA showed excellent stability, including photostability, cycling stability, storage and solvent stability, which made N, S, B-CDs@CA very attractive for practical applications. Additionally, the introduction of Fe³⁺ led to significant quenching of both fluorescence and phosphorescence intensity in the N, S, B-CDs@CA system, establishing a dual-channel detection platform for Fe³⁺. Meanwhile, the quenching mechanisms of fluorescence and phosphorescence of N, S, B-CDs@CA were mainly the static quenching effect. Furthermore, the N, S, B-CDs@CA showed the great potential for the anti-counterfeiting and information encryption. This work developed a novel RTP material with facile preparation procedures, demonstrating potential applications in both ion detection and data encryption.