Nano Lett. 15, 7684–7690 (2015)

In surface-enhanced Raman spectroscopy (SERS), Raman scattering is strongly amplified by placing molecules in close proximity to a metal surface. Surface roughening is generally thought of as the simplest way to improve SERS sensitivity, but a variety of more precise methods have been explored including decorating substrates with metal nanoparticles and using two-dimensional hybrid structures composed of metal nanoparticles on graphene. SungWoo Nam and colleagues at the University of Illinois at Urbana-Champaign have now shown that SERS enhancements can be achieved by simply changing the dimensionality of such graphene structures.

The researchers began by fabricating a graphene film decorated with gold nanoparticles. This was transferred onto a polymer substrate that shrinks when heated, which allowed crumpled graphene–nanoparticle hybrid structures to be created. The three-dimensional graphene structures could then be transferred to a variety of arbitrarily shaped curved surfaces. Compared with similar two-dimensional hybrid systems, the crumpled substrates offer a one order of magnitude stronger Raman signal. Nam and colleagues also suggest that further enhancement could potentially be achieved by tuning the size and spacing between the nanoparticles.