Abstract
Heavy metal ion pollution is always a serious problem worldwide. Therefore, monitoring heavy metal ions in environmental water is a crucial and difficult step to ensure the safety of people and the environment. A mercury ion (Hg
2+
) fluorescence probe with excellent sensitivity and selectivity is described here. The functionalized graphitic carbon nitride nanosheets (T/G-C
3
N
4
) fluorescence probe was fabricated using melamine as a precursor by the pyrolysis technique, followed by a rapid KOH heat treatment method for 2 min. The chemical structure and morphology of the T/G-C
3
N
4
probe were characterized using multiple analytical techniques including UV–Vis, SEM, XPS, XRD, and fluorometer spectroscopy. Geometry optimization of T/G-C
3
N
4
as a modified probe was performed to assess its stability and interaction ability with Hg(II) via using the density function approach. The T/G-C
3
N
4
probe showed a linear response based on quenching over the range 0–1.25 × 10
3
nM Hg(II); the detection limit was 27 nM. The remarkable sensitivity of T/G-C
3
N
4
towards the Hg
2+
ions was explained by the intense coordination and fast chelation kinetics of Hg
2+
with the NH
2
, CN, C=N, and OH groups of T/G-C
3
N
4
nanoprobe. The T/G-C
3
N
4
probe demonstrates exceptional selectivity for Hg
2+
ions among other metal ions including (Na
+
, Ag
+
, Mg
2+
, Fe
2+
, Fe
3+
, Co
2+
, Ni
2+
, Cd
2+
, K
+
, Ca
2+
, Cu
2+
, Pb
2+
, Mn
2+
and Hg
2+
) and over a broad pH range (6–10), together with remarkable long-term fluorescence stability in water (> 30 days) and minimal toxicity. T/G-C
3
N
4
was used to detect and quantify Hg
2+
ions in tuna and mackerel fish and the results compared to ICP-AES. The results obtained offer a new simple and green technique for the design of multifunctional fluorescent probe appropriate for environmental applications.
Graphical Abstract