Nitrogen-Doped Silver-Nanoparticle-Decorated Transition-Metal Dichalcogenides as Surface-Enhanced Raman Scattering Substrates for Sensing Polycyclic Aromatic Hydrocarbons

Abstract

The modification of transition-metal dichalcogenides (TMDs), incorporating nitrogen (N) doping and silver nanoparticles (Ag NPs ) decoration on the skeleton of exfoliated MoS 2 and WS 2 , was accomplished. The preparation of N-doped and Ag NPs -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 NPs -decorated MoS 2 and WS 2 hybrids, abbreviated as N5-MoS 2 /Ag NPs , N10-MoS 2 /Ag NPs , N5-WS 2 /Ag NPs , and N10-WS 2 /Ag NPs , respectively, for each functionalization time. The successful incorporation of N as the dopant within the lattice of exfoliated MoS 2 and WS 2 as well as the deposition of Ag NPs on their surface, yielding N-MoS 2 /Ag NPs and N-WS 2 /Ag NPs , 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 NPs in the modified TMDs. Also, the morphologies of N-MoS 2 /Ag NPs and N-WS 2 /Ag NPs 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 2 /Ag NPs showed the highest sensitivity for detecting RhB at concentrations as low as 10 −9 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 2 /Ag NPs , were screened with high sensitivity and reproducibility. These findings highlight the excellent functionality of the newly developed N-MoS 2 /Ag NPs and N-WS 2 /Ag NPs hybrid materials as SERS substrates for sensing widespread organic and environmental pollutants as well as carcinogen and mutagen species.

Defect engineering in semiconductor-based SERS

“…Anionic doping with non-metallic impurities have been extensively studied, particularly in two-dimensional materials [52][53][54][55][56][57][58][59][60] . Nitrogen, a commonly used reductive dopant, can be easily introduced into the host structure by sample-treatment in NH3 or N2 atmosphere.…”

“…Anionic doping with non-metallic impurities has been extensively studied, particularly in two-dimensional materials. [52][53][54][55][56][57][58][59][60] Nitrogen, a commonly used reductive dopant, can be easily introduced into the host structure by sample-treatment in a NH 3 or N 2 atmosphere. Feng et al 61 showed signicantly boosted SERS sensitivity in N-doped graphene, with an impressive detection level of 5 Â 10 À11 M for RhB (Fig.…”

Two‐Dimensional Nitrogen‐Doped Ti3C2 Promoted Catalysis Performance of Silver Nanozyme for Ultrasensitive Detection of Hydrogen Peroxide

“…The reason for this structure was that N was the nucleation and anchoring point for the growth of Ag nanocrystals. Furthermore, empty d‐orbital Ag nanocrystals produced greater single‐pair electron crosslinking with N atoms, which reduced AgNPs agglomeration [29] . Because of GCE′s weak conductivity and high surface energy, a lot of tiny AgNPs clumped together and exhibited a chaotic distribution.…”

“…Furthermore, empty d-orbital Ag nanocrystals produced greater singlepair electron crosslinking with N atoms, which reduced AgNPs agglomeration. [29] Because of GCE's weak conductivity and high surface energy, a lot of tiny AgNPs clumped together and exhibited a chaotic distribution. NÀ Ti 3 C 2 , on the other hand, had the large specific surface area and strong conductivity, promoting an electron transfer channel between the electroactive surface and the electrolyte solution.…”

A brief review on plasma for synthesis and processing of electrode materials

“…In short, N-plasma has received tremendous interest in N-doping of carbon and nitridization of metal-based materials for energy conversion and storage applications. It is noted that N-doping in metal-based composites via plasma techniques has also improved their performance in some other areas such as photovoltaic response, photoluminescence and electronics [42,181,182].…”