Optimized field confinement and plasmon-induced SERS activity of Janus-like Au–AgAuS hybrid nanoboats

Janus-like Au–AgAuS hybrid nanoboats (NBs) with controllable half shells were prepared by using seed-mediated growth method. Their tunable plasmon properties were investigated by using UV-Vis spectra and finite-difference time-domain (FDTD) method. With the shell thicknesses increasing, the red shifting of surface plasmon resonance (SPR) peaks and an obvious enhancement of transverse SPR band have been observed for the Janus-like NBs. The effects of shell thicknesses and covered areas on local electric field of Janus-like Au–AgAuS NBs were further studied by FDTD simulation, which proposed an effective method to manipulate the electromagnetic field distributions of metal plasmonic nanostructures. In addition, served as solution-based active SERS substrates, the SERS performances of Au NRs and Janus-like Au–AgAuS NBs with different shell thicknesses have been further estimated by using rhodamine B as probe molecules. Compared with the others, Au–AgAuS NBs with about 2.82-nm shell displayed the best SERS performance with good reproducibility in our experiments, owing to the effective plasmonic enhancement and load capability.