One-step synthesis of N, B-doped carbon dots and their multifunctional applications in the detection of tin ions and gallic acid and information encryption

In this work, easily accessible carbon dots (N, B-CDs) were synthesized via a one-step microwave method. In the powder state, N, B-CDs exhibited bright blue fluorescence and stable green phosphorescence with a lifetime of 539 ms, visible to the naked eye for 9 s. Due to their excellent phosphorescent properties, N, B-CDs have been successfully applied in information encryption. Graphic security and information encryption schemes were designed using N, B-CDs and rhodamine 6G. N, B-CDs contained many hydroxyl and amino groups on the surface, which can be utilized to detect specific ions and compounds. N, B-CDs have been successfully applied to detect Sn2+ and gallic acid (GA). Theoretical calculations and mechanistic studies suggested that the sensing of Sn2+ was attributed to the photoinduced electron transfer between Sn2+ and N, B-CDs, and the limit of detection (LOD) was determined as 3.5 μM with the 3s/k rule. In addition, N, B-CDs and GA form cross-links, as determined by Fourier transform infrared spectral analysis, with an LOD of 0.35 μM with the 3s/k rule.