1 research outputs found
Nitrogen-Doped Silver-Nanoparticle-Decorated Transition-Metal Dichalcogenides as Surface-Enhanced Raman Scattering Substrates for Sensing Polycyclic Aromatic Hydrocarbons
The
modification of transition-metal dichalcogenides (TMDs), incorporating
nitrogen (N) doping and silver nanoparticles (Ag<sub>NPs</sub>) decoration
on the skeleton of exfoliated MoS<sub>2</sub> and WS<sub>2</sub>,
was accomplished. The preparation of N-doped and Ag<sub>NPs</sub>-decorated
TMDs involved a one-pot treatment procedure in a vacuum-sputtering
chamber under N plasma conditions and in the presence of a silver
(Ag) cathode as the source. Two different deposition times, 5 and
10 s, respectively, were applied to obtain N-doped with Ag<sub>NPs</sub>-decorated MoS<sub>2</sub> and WS<sub>2</sub> hybrids, abbreviated
as N5-MoS<sub>2</sub>/Ag<sub>NPs</sub>, N10-MoS<sub>2</sub>/Ag<sub>NPs</sub>, N5-WS<sub>2</sub>/Ag<sub>NPs</sub>, and N10-WS<sub>2</sub>/Ag<sub>NPs</sub>, respectively, for each functionalization time.
The successful incorporation of N as the dopant within the lattice
of exfoliated MoS<sub>2</sub> and WS<sub>2</sub> as well as the deposition
of Ag<sub>NPs</sub> on their surface, yielding N-MoS<sub>2</sub>/Ag<sub>NPs</sub> and N-WS<sub>2</sub>/Ag<sub>NPs</sub>, was manifested through
extensive X-ray photoelectron spectroscopy measurements. The observation
of peaks at ∼398 eV derived from covalently bonded N and the
evolution of a doublet of peaks at ∼370 eV guaranteed the presence
of Ag<sub>NPs</sub> in the modified TMDs. Also, the morphologies of
N-MoS<sub>2</sub>/Ag<sub>NPs</sub> and N-WS<sub>2</sub>/Ag<sub>NPs</sub> were examined by transmission electron microscopy, which proved
that Ag deposition resulted in nanoparticle growth rather than the
creation of a continuous metal film on the TMD sheets. Next, the newly
developed hybrid materials were proven to be efficient surface-enhanced
Raman scattering (SERS) platforms by achieving the detection of Rhodamine
B (RhB). Markedly, N10-MoS<sub>2</sub>/Ag<sub>NPs</sub> showed the
highest sensitivity for detecting RhB at concentrations as low as
10<sup>–9</sup> M. Charge-transfer interactions between RhB
and the modified TMDs, together with the polarized character of the
system causing dipole–dipole coupling interactions, were determined
as the main mechanisms to induce the Raman scattering enhancement.
Finally, polycyclic aromatic hydrocarbons such as pyrene, anthracene,
and 2,3-dihydroxynaphthalene, coordinated via π–S interactions
with N-MoS<sub>2</sub>/Ag<sub>NPs</sub>, were screened with high sensitivity
and reproducibility. These findings highlight the excellent functionality
of the newly developed N-MoS<sub>2</sub>/Ag<sub>NPs</sub> and N-WS<sub>2</sub>/Ag<sub>NPs</sub> hybrid materials as SERS substrates for
sensing widespread organic and environmental pollutants as well as
carcinogen and mutagen species