A New Sulfur-Doped Source and Synergistic Effect with Nitrogen for Carbon Dots Produced from Glucose

The nitrogen and sulfur-co-doped carbon dots (N, S-CDs) with increased luminescence were synthesized by hydrothermal process in one green pot by glucose, and a new sulfur-doped source of sodium sulfite was developed. The synergistic effect mechanism of the N and S groups were well discussed through the structure analysis of Fourier transform infrared spectra and X-ray photoelectron spectra. The surface states of N, S-CDs embody more complicated functional groups, and S element exists as -SSO3, -C-SO3 and SO4 2- group due to the introduction of sodium sulfite. The sulfur-containing groups passivate the surface of CDs, and the relatively high sulfur groups may reduce the non-radiation centers. The fluorescence is affected by hydroxyl group of the solvent. The quenching of Fe3+ ion to fluorescence and the sensitivity of pH to fluorescence was also investigated.