Background: Dichromate (Cr2O7
2-) ion is one of the carcinogenic and toxic spices in
environment which can easily contaminate the environment due to its high solubility in water. Therefore,
a lot of attention has been focused on the detection of Cr2O7
2- with high sensitivity and selectivity.
Methods: In present work, nitrogen-rich precursor was used for synthesizing graphitic carbon nitride
(g-C3N4) nanostructures through hydrothermal oxidation of g-C3N4 nanosheets. The prepared
nanostructures show two distinct fluorescence emissions centered at 368 and 450 nm which are highly
sensitive toward Cr2O7
Results: The as-prepared g-C3N4 was characterized by several techniques such as Fourier-Transform
Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and
fluorescence emission spectra. The XRD pattern of prepared nanostructures illustrated two diffraction
patterns (at 13.4° and 27.6°) indicating tri-s-tri-azine-based structures. The g-C3N4 exhibited good selectivity
and sensitivity toward Cr2O7
2- among other anions. According to titration test, the detection
limit and stern-volmer constant (Ksv) were calculated as 40 nM and 0.13×106 M-1, respectively. The
investigation of quenching mechanism shows that Cr2O7
2- may form hydrogen bonding with surface
groups of g-C3N4 (such as NH2, OH and COOH) resulted in more fluorescence quenching in comparison
with the pure inner filter effect.
Conclusion: The g-C3N4 nanostructures were successfully synthesized through the hydrothermal oxidation.
The as-prepared g-C3N4 can be used as a highly sensitive fluorescent probe for the selective
determination of Cr2O7
2 ion among other anions. The quenching mechanism was experimentally studied.
According to reliable responses in real sample tests, it can be proposed that g-C3N4 nanostructure
is a suitable sensitive nanosensor for detection of Cr2O7
2 ions in aqueous media.