Water-soluble graphitized carbon dots (GCDs) were synthesized by the one-step carbonization of ethylene glycol (EG) at 140 degrees C in the presence of concentrated sulfuric acid (H2SO4). Without any post-passivation, their quantum yield (QY) of photoluminescence (PL) reached 25%. The fluorescence of GCDs was located at about 400nm with a full width at half maximum (FWHM) as small as similar to 59 nm. The nearly invariable PL position in certain range of excitation wavelength concluded that the good PL of GCDs should be assigned to the bandlike transition similar to general semiconductor. Further investigation showed that they could be used as a label-free fluorescent probe in the selective and sensitive detection of Hg2+. (C) 2012 Elsevier B. V. All rights reserved.