Tunable luminescence carbon dots (C-dots) were prepared through microwaveassisted carbonization of aqueous starch suspension mediated by sulfuric and phosphoric acids respectively as surface passivating agents. The as-prepared C-dots showed green, blue and yellow luminescence under 365nm UV light. The C-dots were further characterized by UV-Vis, FTIR, and band gap determination. Fourier transform infrared spectroscopy (FTIR) studies revealed bands at 3460 cm-1 (OH), 2979 cm-1 1708 cm-1 (C=O), 1188 and 1040cm-1 (C-O), and 1397 cm-1 (C=C) indicative of the graphitic nature of the carbon. The UV-Vis showed blue shifted absorption bands, while the band gap calculated revealed narrow sizing of the C-dots in the semiconductor range. The results suggest that this approach may serve as a facile route to colour tunable photoluminescent C-dot materials with potential biological applications.
