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 × 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 × 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.