2D TiS₂‐Nanosheet‐Coated Concave Gold Arrays with Triple‐Coupled Resonances as Sensitive SERS Substrates

Abstract

Herein, a hybrid substrate for surface‐enhanced Raman scattering (SERS) is fabricated, which couples localized surface plasmon resonance (LSPR), charge transfer (CT) resonance, and molecular resonance. Exfoliated 2D TiS2 nanosheets with semimetallic properties accelerate the CT with the tested analytes, inducing a remarkable chemical mechanism enhancement. In addition, the LSPR effect is coupled with a concave gold array located underneath the thin TiS2 nanosheet, providing a strong electromagnetic enhancement. The concave gold array is prepared by etching silicone nanospheres assembled on larger polystyrene nanospheres, followed by depositing a gold layer. The LSPR intensity near the gold layer can be adjusted by changing the layer thickness to couple the molecular and CT resonances, in order to maximize the SERS enhancement. The best SERS performance is recorded on TiS2‐nanosheet‐coated plasmonic substrates, with a detectable methylene blue concentration down to 10−13 m and an enhancement factor of 2.1 × 109 and this concentration is several orders of magnitude lower than that of the TiS2 nanosheet (10−11 m) and plasmonic substrates (10−9 m). The present hybrid substrate with triple‐coupled resonance further shows significant advantages in the label‐free monitoring of curcumin (a widely applied drug for treating multiple cancers and inflammations) in serum and urine.

Phase Transformation on Multilayer 2M-WS2 for Improved Surface-enhanced Raman Scattering

“…However, the synthesis of single-layer TMDCs is still difficult, and multilayer TMDCs are more suitable for SERS sensing due to their easy preparation and stable performance. Currently, various strategies, such as atomic doping, the noble metal coupling, , and the creation of 2D heterojunctions, , have emerged as critical approaches for bolstering the CT capabilities of semiconducting-phase TMDCs.…”