Abstract
Dual-emissive carbon dots (CDs) hold significant potential for sensing and bioimaging, but achieving intrinsic, precisely controlled dual emissions with self-calibration capability without post-modification remains challenging. Herein, a novel in situ synthesis of dual-emissive CDs using pyronin Y as the sole precursor via a one-pot hydrothermal method is presented. This strategy directly generates CDs exhibiting homogeneous dual-fluorescence and intrinsic self-calibration properties. Systematic investigation reveals that the dual emissions arise from the synergistic interplay between green emission centers scattered on the carbon core and orange-emissive surface-bound aromatic molecular fluorophores derived from the precursor. Green emission centers form rapidly at 160 °C (8 h reaction), comprising three-ring aromatics functionalized with aldehyde, amide, amino, hydroxyl, and methyl groups. Leveraging this unique optical signature, a ratiometric fluorescent sensor is fabricated for hydrogen sulfide (H2S) detection, achieving rapid, highly sensitive (detection limit: 6.93 nm), and selective sensing over a wide range (10 nm–70 µm). Furthermore, the CDs enable effective ratiometric imaging of exogenous and endogenous H2S in living cells. This single-precursor approach provides a versatile platform for intrinsically dual-emissive nanomaterials and advances the rational design of high-performance sensing and bioimaging agents through fundamental mechanistic insights.