Reduction of Congo red using nitrogen doped fluorescent carbon nanodots obtained from sprout extract of Borassus flabellifer

Here, we have demonstrated a facile hydrothermal carbonization pathway for the fabrication of luminescent nitrogen doped carbon nanodots (N-CNDs). The sprout extract of Borassus flabellifer (B. flabellifer) and aquous ammonia (aq.NH3) were utilized as a source of carbon and nitrogen, respectively. Using diverse microscopic and spectroscopic methods, the fabricated N-CNDs were characterized and reported. The excitation dependant emission and absorbance features of the prepared N-CNDs were studied using fluorescence and UV-Visible spectroscopic methods. When excited at 320 nm the obtained N-CNDs exposed deep blue emission at 405 nm. The quantum yield (QY) for the synthesized N-CNDs was found to be 41%. The HR-TEM results confirmed the spherical shape and the size of the prepared N-CNDs to be 2.37 nm. The amorphous character of the synthesized N-CNDs was revealed by SAED pattern, XRD and Raman spectroscopic studies. Doping of nitrogen over surface of the CNDs was examined and confirmed through FT-IR, XPS and EDS analyses. XPS and FT-IR studies also exposed the presence of -COOH, -NH2, -OH and -C=O functional groups over the N-CNDs surface. The synthesized N-CNDs were found to have profound catalytic effect on the reduction of congo red by NaBH4. Thus the study has unravelled the nature and utility of N-CNDs from B. flabellifer.