Synthesis of dual-emissive carbon dots with a unique solvatochromism phenomenon.

Carbon dots as an emerging photoluminescent material has attracted growing attention. Hence, there is a highly urgent to develop kinds of multicolor emission carbon dots materials. Here, we report a new kind of dual-emissive carbon dots which display two emission band located at 457 and 643 nm (blue and red) in alcohols solvent, respectively. In particular, the red emission band of carbon dots independent of the excitation wavelength can be manipulated by changing the polarity of the solvent, which is called solvatochromic phenomenon. It is incredibly rare for bare carbon dots to have both dual-emission and solvatochromic phenomenon at the same time. The temperature-dependent emission spectra of synthesized carbon dots have been measured to go insight into the hydrogen bond interaction, and the aggregation in microscale is observed by transmission electron microscopy. Results indicates that the special dual-emission and solvatochromic phenomenon stem from partially nanoparticle agglomerates which caused by intermolecular hydrogen bond (between solvents and carbon dots). Benefiting from the special optical characteristics, the applications of ratiometric detecting water in ethanol was carried out.