Highly Reproducible Surface-Enhanced Raman Spectra on Semiconductor SnO2 Octahedral Nanoparticles

Highly reproducible surface-enhanced Raman scattering (SERS) spectra are obtained on the surface of SnO2 octahedral nanoparticles. The spot-to-spot SERS signals show a relative standard deviation (RSD) consistently below 20?% in the intensity of the main Raman peaks of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NBT), indicating good spatial uniformity and reproducibility. The SERS signals are believed to mainly originate from a charge-transfer (CT) mechanism. Time-dependent density functional theory (TD-DFT) is used to simulate the SERS spectrum and interpret the chemical enhancement mechanism in the experiment. The research extends the application of SERS and also establishes a new uniform SERS substrate.