Synthesis of <i>o</i> -phenylenediamine-based Zn-doped carbon dots with excitation-independent emission for the qualitative detection of ClO ⁻

Herein, o -phenylenediamine-based Zn-doped carbon dots (Zn-CDs) were hydrothermally synthesized using o -phenylenediamine, zinc sulfate heptahydrate, and aniline. The prepared Zn-CDs contained crystalline carbon with particle sizes ranging from approximately 3 to 7 nm. Remarkably, Zn-CDs displayed emission that was independent of excitation, peaking at 553 nm. The fluorescence diminished in acidic aqueous solutions, while metal ions had minimal effect on their properties. Addition of ABTS •+ led to a quenching of fluorescence with a calculated EC 50 value of 4.0887 × 10 -3 g/L. Additionally, an oxidation-reduction reaction occurred between ClO − and Zn-CDs, leading to notable reductions in fluorescence and the generation of a fluorescence peak at around 490 nm. Zn-CDs showed selectivity towards ClO − because of the absence of interaction between Zn-CDs and H 2 O 2 , NO, and ROO • . This work presents a novel approach to prepare Zn-CDs with excitation-independent emission and expands the application of Zn-CDs for color-changing and qualitative detection of ClO − .