Exploring of multicolor emissive carbon dots with novel double emission mechanism

Multicolor emissive carbon dots (CDs) was successfully synthesized via a facile one-pot solvothermal method with the assistance of ethanol, which is nominated as E-CDs. In the reaction system, the addition of ethanol plays a key role in synthesizing CDs with higher proportion of amorphous structures, resulting in multicolor emission of the E-CDs after dissolved in various solvents. Moreover, this solvent dependent multicolor emission of the E CDs is found to be ascribed to a novel double emission mechanism. The excitation dependent blue emissions stem from intrinsic surface/defect states of the E-CDs while the excitation independent long wavelength emissions originate from solvent molecules connected on the surface of the E-CDs via hydrogen bond. Noticeably, the hydrogen bond between the E-CDs and surrounding environment endows the prepared E-CDs with a unique pH sensitive feature, which can be used to construct fluorescent pH sensor. Besides, based on this multicolor emission, the E-CDs show potential in bio-labeling, multicolor patterning and solid luminous materials.