  Atomically thin boron nitride (BN) nanosheets have many properties desirable
for surface enhanced Raman spectroscopy (SERS). BN nanosheets have a strong
surface adsorption capability towards airborne hydrocarbon and aromatic
molecules. For maximized adsorption area and hence SERS sensitivity, atomically
thin BN nanosheet covered gold nanoparticles have been prepared for the first
time. When placed on top of metal nanoparticles, atomically thin BN nanosheets
closely follow their contours so that the plasmonic hot spots are retained.
Electrically insulating BN nanosheets also act as a barrier layer to eliminate
metal-induced disturbance in SERS. Moreover, the SERS substrates veiled by BN
nanosheets show an outstanding reusability in the long term. As the result, the
sensitivity, reproducibility and reusability of SERS substrates can be greatly
improved. We also demonstrate that large BN nanosheets produced by chemical
vapor deposition can be used to scale up the proposed SERS substrate for
practical application.
