1. We have demonstrated a facile synthesis of N-GQDs from the carbonization of citric acid through hydrothermal treatment in the presence of ammonia.
2. These synthesized N-GQDs were mostly composed of 1–3 layers with a uniform size of about 3.5 nm, and their N/C ratios were controlled by the amount of ammonia.
3. The N-GQDs also exhibit bright blue-luminescence with higher PL quantum yield than GQDs which show green-luminescence.
4. Furthermore, we have demonstrated that N-GQDs can be used as fluorescence probes for the detection of Fe3+ ions with high selectivity and sensitivity.
5. Our approach represents a green, inexpensive and convenient method for large-scale production of N-GQDs.
6. The N-GQDs synthesized by this process can potentially be used in various