Highly Sensitive Surface Enhanced Raman Spectroscopy from Ag Nanoparticles Decorated Graphene Sheet

Figure 2

SEM images of sample A to F for different immersing time spans (white reticular lines are the grain boundary of single crystal graphene domains). The coverage of the Ag NPs decoration varied from 7.5% for 1 s (sample A) to 19.1% for 40 s (sample E). The Ag NPs prefer to decorate along the boundaries of graphene domain. The diameter of spherical Ag NPs is varied from 10–40 nm for 1 s to 80–140 nm for 40 s. The quasi cubic Ag NPs aggregate along the boundaries of graphene domains and form a quasi-continuous film when the immersing time is longer than 2 minutes. All scale bar 1 μm and inset 100 nm.

(a) Sample A, 1 s

(b) Sample B, 5 s

(c) Sample C, 10 s

(d) Sample D, 20 s

(e) Sample E, 40 s

(f) Sample F, 120 s