Abstract
Surface-enhanced Raman scattering (SERS) has been extensively investigated as an effective approach for trace species detection. Silver nanostructures are high-sensitivity SERS substrates in common use, but their poor chemical stability impedes practical applications. Herein, a stable and sensitive SERS substrate based on the hybrid structures of graphene/silver film/laser-textured Si (G/Ag/LTSi) was developed, and a simple, rapid, and low-cost fabrication approach was explored. Abundant nanoparticles were directly created and deposited on the Si surface via laser ablation. These aggregated nanoparticles functioned as hotspots after a 30 nm Ag film coating. A monolayer graphene was transferred to the Ag film surface to prevent the Ag from oxidation. The SERS behavior was investigated by detecting R6G and 4-MBT molecules. The experimental results indicate that the maximum enhancement factor achieved by the G/Ag/LTSi substrate is over 107 and less than 23% SERS signals lost when the substrate was exposed to ambient conditions for 50 days. The covering graphene layer played crucial roles in both the Raman signals enhancement and the Ag nanostructure protection. The stable and sensitive SERS performance of G/Ag/LTSi substrate evince that the present strategy is a useful and convenient route to fabricate large-area graphene-silver plasmonic hybrids for SERS applications.
Highlights
Trace species detection is important in our daily life, such as in the fields of food safety, environmental monitoring, and disease diagnosis
System, which derives from the charge transfer between the analytical molecules and Surface-enhanced Raman scattering (SERS) substrates with an enhancement factor (EF) of around 10–100
The results show that the content of oxygen element on Si surface increases from nearly 0–11% after laser ablation at a laser fluence of 15 J/cm2
Summary
Trace species detection is important in our daily life, such as in the fields of food safety, environmental monitoring, and disease diagnosis. Graphene is a single layer of sp2 -bonded carbon atoms densely packed into two-dimensional honeycomb crystal lattices with fascinating properties, such as atomic thickness, high optical transparency, chemical inertness, biological compatibility, excellent flexibility, and impenetrability to gas molecules Such merits endow graphene as an ideal material for the protective layer/shell in SERS applications. Motivated by the above-mentioned advantages of graphene and laser ablation, we provide a rapid, simple, and low-cost approach to fabricate sensitive and stable graphene-silver plasmonic hybrids for SERS applications This substrate is combined of single-layer graphene, Ag film and laser-textured Si surface, forming the hybrid graphene/Ag/laser-textured Si (G/Ag/LTSi) structure. Using rhodamine 6G (R6G) and 4-methylbenzenethiol (4-MBT) molecules as probe molecules, the G/Ag/LTSi substrate exhibits stable and sensitive SERS performance
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