Gram scale synthesis of green fluorescent water-soluble onion-like carbon nanoparticles from camphor and polystyrene foam

Herein, we report a cost effective and simple method for gram scale synthesis of water-soluble onion-like carbon nanoparticles (wsOCNPs) using common carbonaceous sources like camphor and polystyrene foam. The synthetic methodology involves ambient burning of these carbon rich materials under an insufficient oxygenic atmosphere. Furthermore, the oxidative treatment of carbon soot (CS) imposes dense carboxylic group functionalization over the surface of wsOCNPs. The high degree of surface functionalization imposes a self-passivated fluorescence effect along with photostability, which makes the material a potential candidate for bio-imaging purposes. Surprisingly, these wsOCNPs show exceptional excitation wavelength independent fluorescence emission properties over a wide region of the visible spectrum.