Highly active SERS chip with both structure-ameliorated chemical enhancement and nanocavity-mediated electromagnetic enhancement

An essential aspect for the wide practical application of surface-enhanced Raman spectroscopy (SERS) lies in the further improvement of its sensitivity. In this paper, a strengthened chemical effect with a high enhancement factor (EF) of 3.9 x 107 was first triggered through simply adjusting the heterojunction structure between graphitic carbon nitride (g-C3N4) flake and molybdenum disulfide (MoS2) nanoflower. Ag nanoparticles (Ag NPs) were then photo-reduced onto the g-C3N4 @MoS2 matrix to introduce significant steric electromagnetic field under excitation, which was further reinforced by provoking a resonance coupling effect based on graphene oxide (GO) resonant cavity. Such a cavity was set between the g-C3N4 @MoS2 @Ag-polydimethylsiloxane (PDMS) matrix and the Ag nanocubes (Ag NCs)-embedded PDMS coating membrane, facilitating a robust flexible SERS chip with a promising EF attained as 1.1 x 109. Additionally, the SERS intensity was only decreased by 5% after three months, indicating the excellent stability of the as-prepared bilayer SERS chip. The on-site reclaimable monitoring for thiram (TMTD) and methyl parathion (MP) accompanied by a low limit of detection (LOD) of 10-6 mg/mL was achieved by utilizing the proposed sophisticated SERS chip, demonstrating its fascinating application feasibility.

Automated summary

In this paper, an enhanced SERS chip with high sensitivity was developed by adjusting the heterojunction structure and resonance coupling effect. The chip showed excellent stability and demonstrated promising application feasibility in on-site monitoring of TMTD and MP with low detection limit.