The structure and properties of graphene on gold nanoparticles

Abstract

Graphene covered metal nanoparticles constitute a novel type of hybrid materials, which provide a unique platform to study plasmonic effects, surface-enhanced Raman scattering (SERS), and metal-graphene interactions at the nanoscale. Such a hybrid material is fabricated by transferring 2 graphene grown by chemical vapor deposition onto closely spaced gold nanoparticles produced on a silica wafer. The morphology and physical properties of nanoparticle-supported graphene is investigated by atomic force microscopy, optical reflectance spectroscopy, scanning tunneling microscopy and spectroscopy (STM/STS), and confocal Raman spectroscopy. This study shows that the graphene Raman peaks are enhanced by a factor which depends on the excitation wavelength, in accordance with the surface plasmon resonance of the gold nanoparticles, and also on the graphene-nanoparticle distance which is tuned by annealing at moderate temperatures. The observed SERS activity is correlated to the nanoscale corrugation of graphene.STM and STS measurements show that the local density of electronic states in graphene is modulated by the underlying gold nanoparticles.

Surface-Enhanced Raman Spectroscopy of Graphene Integrated in Plasmonic Silicon Platforms with Three-Dimensional Nanotopography

“…For this substrate, the highest measured enhancement factor is F = 880 for the G peak and F = 420 for the 2D peak, both under 633 nm excitation wavelength. These values are similar to the highest measured enhancement factors reported in literature (~1000) for SERS of graphene on plasmonic substrates [17][18][19][20][21][22][23][24][25][26][27][28] . A higher enhancement is achieved when graphene is placed on top of plasmonic structures, as in this work, than when it is placed below them.…”

Reduced Graphene Oxide and Its Natural Counterpart Shungite Carbon

“…A large spectrum of traces of different metals, including Ni, Cu, Ag, Au, and some others, is known for shungite rocks [22] due to which the presence of the relevant nanoparticles is highly probable. The basic graphene fragments, enveloping metal nanoparticles, curve similarly to what was shown experimentally for a graphene sheet superimposed on a place of gold nanoparticles [23].…”

Nanoparticle Clusters: Assembly and Control Over Internal Order, Current Capabilities, and Future Potential

“…The coupled plasmon modes are generally red-shifted compared to the single-particle modes, where the extent of the shift depends sensitively on d ss . The emergence of a high-intensity local electromagnetic field upon coupling was extensively used in the past to modulate near-field associated processes, such as absorption or emission modulation of chromophores, as well as surface enhanced Raman scattering (SERS), [66] where, especially at hot-spots, the large electromagnetic-field enhancement can enable the increase the strength of the otherwise very weak Raman signal. Provided the structure of a plasmonic NPC is properly controlled, it holds the promise for large effective Raman-signal enhancement, due to the high number density of hot-spots.…”