One-step synthesis of intrinsically functionalized fluorescent carbon nanoparticles by hydrothermal carbonization from different carbon sources

Highly functionalized carbon nanoparticles (F-CNPs) with average sizes of 5–30 nm were fabricated by hydrothermal carbonization of specific carbon sources at a mild temperature without usual strong acid treatment or surface modification. The morphology, structure, and fluorescent properties of the nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, Raman spectra and fluorescent spectrophotometer. As a result, the abundant carboxylic, sulfonic, amine, or ethanamide groups were furnished on the surface of these carbon nanoparticles, offering the reaction sites for their possible further functionalization, and these functional groups also enhance the dispersion of carbon nanoparticles which are kept without precipitation for months. The hydrothermal treatment which is simple, green, and economical, also can endow the F-CNPs much more carboxyl groups, thus improving the quantum efficiency of as-prepared products. These functionalized carbon nanoparticles demonstrate the excitation wavelength-independent photoluminescence behavior, implying their potential applications in biological labeling, imaging, and chromatography.