Surface plasmon resonance effect on charge transfer in Ag@Cu2O-rGO composites

Abstract

We designed the Ag@Cu2O core-shell structure in situ growth on the reduced graphene oxide (rGO). The proposed Ag@Cu2O-rGO composite demonstrated superior surface-enhanced Raman scattering (SERS) activity for quantitative analysis of the targets. In this study, the Ag nanoparticles (NPs) produce strong surface plasmon resonance (SPR), and Cu2O has advantages such as a narrow band gap and a strong ability to capture visible light. Most importantly, the Schottky effect in the noble metal/semiconductor composite promotes high SERS activity. The two-dimensional material was used as a platform to promote electron transport between the noble metal and semiconductor. It was found that SERS enhancement is dependent on the thickness of the shell, which was affected by the transfer of hot electrons and the contribution of the SPR of Ag NPs. As the Cu2O shell thickness is 16 nm, its addition not only increases the molecular adsorption capacity but also does not affect the SPR of Ag due to its thinness. In addition, 10−9 M methylene blue can easily be detected on the optimal Ag@Cu2O-rGO composite. This study proves that the Ag@Cu2O-rGO composite SERS substrate has high sensitivity, and is expected to be widely used in environmental monitoring, medical inspection, food supervision, and other aspects in the future.