Sandwich-structured Ag/graphene/Au hybrid for surface-enhanced Raman scattering

• Sandwich-structured Ag/graphene/Au hybrid was fabricated by electrodeposition.
• Prominent SERS activity was attained on Ag/rGO/Au hybrid.
• Reduction degree of rGO impacted Raman signal of RhB on Ag/rGO/Au nanostructure.
• rGO sheets protected silver dendrites from oxidation under ambient condition.
• Ag/rGO/Au hybrid was useful for the development of SERS-based chemical sensor.

The Ag/graphene/Au nanostructure as an efficient surface enhanced Raman scattering (SERS)-active substrate was fabricated by sandwiching the reduced graphene oxide (rGO) between plasmonic silver dendrites and gold nanoparticles layers by a simple electrodeposition method. The surface plasmons aroused in the Ag-rGO interface could be effectively transferred from the silver to the top gold by rGO interlayer, which favored the higher SERS activity of Ag/rGO/Au hybrid compared to the Ag/rGO and Au/rGO/Au ones due to the more localized plasmon resonance on the gold surface. Furthermore, the reduction degree of rGO interlayer impacted the nucleation and growth of gold on the rGO surface and therefore the Raman signal for Rhodamine B molecules absorbed on the Ag/rGO/Au sandwich nanostructure. The rGO sheets and the top gold nanoparticles film also effectively protected the silver dendrites from oxidation under ambient condition. This Ag/rGO/Au sandwich nanostructure was useful for the development of an efficient SERS-based chemical sensor because of the simply fabrication, adjustable SERS activity, long-term stability and high reproducibility.

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