A theoretical and experimental approach to shell-isolated nanoparticle-enhanced Raman spectroscopy of single-crystal electrodes

Recently we developed shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) as a new variant of surface-enhanced Raman spectroscopy (SERS). The most important feature of SHINERS is its capability to study electrochemical single-crystal electrode surfaces, e.g., gold, platinum, palladium, rhodium and silicon. The gold-core silica-shell nanoparticles can significantly boost the Raman intensity from adsorbates on atomically flat surfaces. Very surprisingly the average enhancement factor can reach 106 for Au(110) and 105 for Pt(110). To understand this extraordinary high enhancement, we explore the mechanism on why SHINERS works so well for single-crystal electrode of diverse materials by classical electromagnetic simulations. We then performed the periodic DFT calculations of the polarizability of clean and pyridine-modified surfaces and the Raman intensity of adsorbates to reveal the interesting phenomenon regarding surface-crystal-orientation dependence of SHINERS intensity. Finally, prospective developments of EC-SHINERS are discussed.