Table 1 Synthesis of CDs from small organic molecules via a top-down approach
S. No. | Source | Method of preparation | Doping (d)/surface passivating (p) agent | Color | Size (nm) | Refs. No. |
|---|---|---|---|---|---|---|
1. | Carbon nanotube | Electrochemical synthesis | – | Blue | 2.8 ± 0.5 | [26] |
2. | Carbon soot | Chemical oxidation | – | Green | 2–6 | [40] |
3. | Carbohydrates | Chemical oxidation | (TTDDA) 4,7,10-trioxa-1,13-tridecanediamine (P) | Red, blue, green and yellow | 5 | [46] |
4. | Low-molecular-weight alcohols | Electrochemical synthesis | – | Red and blue | 2.1, 2.9, 3.5, and 4.3 | [47] |
5. | Sodium citrate and urea. | Electrochemical synthesis | – | Blue | 1.0–3.5 | [48] |
6. | Graphite electrode | Electrochemical synthesis | – | Bright yellow | 4 ± 0.2 | [49] |
7. | Toluene | Laser ablation | – | Red, black and blue | 2–3.9, 3–10.0, 10–17.2 and 13–20.5 | [41] |
8. | Graphite powders | Laser ablation | – | Red, black and blue | 1.5, 1.6, and 1.8 | [50] |
9. | Ascorbic acid and ammonia | Ultrasonic treatment | N (d) | Blue, green | 3.36 | [51] |
10. | Oligomer polyamide resin | Ultrasonic treatment | Silane coupling agent (p) | Bright white | 2–4 | [33] |