A Novel One‐Step Approach to Synthesize Fluorescent Carbon Nanoparticles

Fluorescent carbon nanoparticles (CNPs) were prepared directly by a simple hydrothermal method by using L ‐ascorbic acid as a carbon source. The synthesized CNPs with higher photoluminescence efficiencies (6.79 %) are monodisperse, and their diameter is about 2.0 nm. In contrast to previous methods, for this one‐step process, neither strong acid treatment nor further surface modification is necessary. Aqueous solutions of the CNPs are stable at room temperature for at least half a year. In particular, the fluorescence of the CNPs does not change over a wide pH range and even in solvents with strong ionic strengths (e.g. 2 M NaCl).