Plasmonic Coupling of AgNPs near Graphene Edges: A Cross-Section Strategy for High-Performance SERS Sensing
Ziyang Cao, Peng He, Tao Huang, Siwei Yang, Sancan Han, Ding Wang, Guqiao Ding
Abstract
Fully exploiting plasmonic coupling of nanostructured metals is an effective method to promote surface-enhanced Raman scattering (SERS) performance for trace detection of molecules. Herein, we propose a cross-section strategy to maximize plasmonic coupling of silver nanoparticles (AgNPs) in a graphene-based membrane. Specifically, AgNPs are isolated by water-dispersible graphene (W-Gr) and enriched in the vicinity of W-Gr edges when assembling into a macroscopic membrane, thus affording AgNPs on the cross section with uniform and proper gaps in the vertical plane to generate maximal plasmon coupling. Moreover, the superior sensitivity (5 × 10–13 M for R6G) to most reported graphene–metal structures and the long-term stability against aerobic oxidation jointly make the cross-section of the AgNPs/W-Gr membrane a potential SERS substrate for trace-molecule detection. The revealed mechanism for AgNPs enrichment near edges highlights the importance of the flow-directed assembly process of W-Gr. This work provides new insight into the interpretation and utilization of two-dimensional materials as building blocks in high-performance SERS sensing.