| Περίληψη: | The modification of transition-metal dichalcogenides (TMDs), incorporating nitrogen (N) doping and silver nanoparticles (AgNPs) decoration on the skeleton of exfoliated MoS2 and WS2, was accomplished. The preparation of N-doped and AgNPs-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 AgNPs-decorated MoS2 and WS2 hybrids, abbreviated as N5-MoS2/AgNPs, N10-MoS2/AgNPs, N5-WS2/AgNPs, and N10-WS2/AgNPs, respectively, for each functionalization time. The successful incorporation of N as the dopant within the lattice of exfoliated MoS2 and WS2 as well as the deposition of AgNPs on their surface, yielding N-MoS2/AgNPs and N-WS2/AgNPs, was manifested through extensive X-ray photoelectron spectroscopy measurements. The observation of peaks at â398 eV derived from covalently bonded N and the evolution of a doublet of peaks at â370 eV guaranteed the presence of AgNPs in the modified TMDs. Also, the morphologies of N-MoS2/AgNPs and N-WS2/AgNPs 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-MoS2/AgNPs 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 Ï€-S interactions with N-MoS2/AgNPs, were screened with high sensitivity and reproducibility. These findings highlight the excellent functionality of the newly developed N-MoS2/AgNPs and N-WS2/AgNPs hybrid materials as SERS substrates for sensing widespread organic and environmental pollutants as well as carcinogen and mutagen species. |
