Molybdenum Disulfide Quantum Dots as a Photoluminescence
Sensing Platform for 2,4,6-Trinitrophenol Detection
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Abstract
Transition metal
chalcogenides, especially molybdenum disulfide
(MoS<sub>2</sub>), have recently attracted wide attention from researchers
as graphene-analogous materials. However, until now, little literature
has reported the synthesis of photoluminescent MoS<sub>2</sub> materials
and their applications in analytical chemistry. We herein presented
a facile bottom-up hydrothermal route for the synthesis of photoluminescent
MoS<sub>2</sub> quantum dots (QDs) by using sodium molybdate and cysteine
as precursors. The prepared MoS<sub>2</sub> QDs were characterized
by transmission electron microscopy, atomic force microscopy, X-ray
photoelectron spectroscopy, Fourier transform infrared spectroscopy,
photoluminescence spectroscopy, and UV–vis spectroscopy. The
MoS<sub>2</sub> QDs were then used as photoluminescent probes to construct
a photoluminescence (PL) quenching sensor for detection of 2,4,6-trinitrophenol
(TNP). The TNP sensor presented a wide linear range from 0.099 to
36.5 μM with a high detection limit of 95 nM. Furthermore, the
sensor displayed a high sensitivity toward TNP over other structurally
similar compounds like 2,4,6-trinitrotoluene, p-chlorophenol, phenol,
and 2,6-di-<i>tert</i>-butyl-4-methylphenol. To understand
the origin of the high sensitivity, we assessed the emission wavelength-dependent
PL quenching behavior of MoS<sub>2</sub> QDs by the above five compounds
using Stem–Volmer equation in detail. The results showed that
the novel approach we put forward can satisfactorily explain the interaction
mechanisms between MoS<sub>2</sub> QDs and the five compounds, and
the high sensitivity for TNP very likely originated from a combination
of the PL resonance energy transfer, electronic energy transfer, and
electrostatic interactions between MoS<sub>2</sub> QDs and TNP. Finally,
the sensor was successfully applied for detection of TNP in water
samples and test papers