A universal sugar-blowing approach to synthesize fluorescent nitrogen-doped carbon nanodots for detection of Hg(II)

Highlights: • A novel sugar-blowing approach was developed to synthesize nitrogen-doped carbon nanodots (N-CDs) for the first time. • The tremendous fluorescence quenching of N-CDs dispersion was observed by addition of Hg(II), compared to other metal ions. • A high-performance fluorescent sensing platform based on N-CDs for Hg(II) detection was constructed. Fluorescent carbon nanodots (CDs) have been considered as promising materials for fluorescent sensing applications. However, preparation of CDs-based materials by a universal approach with high product yield is highly required. Herein, a novel sugar-blowing approach was reported to facilely synthesize nitrogen-doped CDs (N-CDs) by directly heating the mixture of glucose and dicyandiamide (DCDA) in the absence of any solvents. As a typical blowing agent to trigger sugar-blowing process, DCDA also serves as an ideal nitrogen dopant for N-CDs. For fluorescent sensing applications, a remarkable fluorescence quenching at 441 nm of N-CDs dispersion was observed after introduction of Hg(II). Consequently, as-synthesized N-CDs behaves as a highly sensitive fluorescent probe for Hg(II) detection with low detection limit of 50 nM and good selectivity. More importantly, our proposed approach is universal for synthesize fluorescent N-CDs from a wide of sugar precursors (glucose, fructose, maltose and lactose) and blowing agents (DCDA, melamine, urea, hexamethylenetetramine). The strategy demonstrated here provides insights into the rational design and synthesis of CDs-based functional materials for large-scale applications in various fields.