Hollow Au nanoparticles for single-molecule Raman spectroscopy via a synergistic electromagnetic and chemical enhancement strategy

The integration of a 2D WS 2 monolayer into a plasmonic nanogap leads to a synergistic enhancement, achieving an unprecedented Raman enhancement factor of 10 14 –10 15 and ultrasensitive single-molecule SERS detection (10 −16 M).