Nitrogen‐Doped Carbon Quantum Dots as a “Turn‐Off” Fluorescent Probes for Highly Selective and Sensitive Detection of Mercury(II) Ions

Abstract

AbstractA facile, economical and straightforward hydrothermal strategy was used to prepare highly luminescent nitrogen‐doped carbon quantum dots (N‐CQDs) by using citric acid and urea as the precursors. The as‐prepared N‐CQDs exhibited excellent excitation‐wavelength‐dependent photoluminescence property, high relative fluorescence quantum yield of up to 82.4%, and high selective response to Hg2+ over other examined metal ions in water samples. Under the optimal conditions, the response was linearly proportional to the Hg2+ concentration in the range of 0–250 μM with a detection limit of 1.3 nM. The established N‐CQDs based fluorescent sensor was then successfully applied for label‐free detection of Hg2+ in environmental water samples (tap, lake, and well water). Satisfactory repeatability, reproducibility, recovery results (92.6‐116.8%) are achieved for the determination of Hg2+ in real water samples.