Facile Synthesis of Water-soluble Carbon Spheres for the Sensitive and Selective Determination of Fe3+, Cr3+, and Hg2+ Ions

Water-soluble carbon spheres (CS) were prepared by a facile one-step hydrothermal synthetic method using glucose as a carbon source and sodium hydroxide as additives. The morphology and the chemical structure were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). In addition, the ultraviolet-visible (UV-vis) absorption spectrum and the fluorescence spectrum of the prepared CS were also investigated. The emission spectrum of the obtained CS depends on the excitation wavelength, which is similar to that of most carbon quantum dots. The fluorescence of the CS is quenched in the presence of Cr3+, Fe3+ and Hg2+. Based on this feature, the selective and sensitive detections of Cr3+, Fe3+ and Hg2+ were performed, and the detection limits were 6.72, 7.26, and 9.51 mu M, respectively.