Optical properties of gold/multilayer-graphene/carbon nanotube hybrid materials

Discrete dipole approximation (DDA) method was utilized to simulate optical properties (extinction spectra and normalized electric field distribution) of multilayer graphene shell encapsulated gold nanoparticles (GNPs) and their heterostructures with carbon nanotube (CNT). The results were also compared with those for gold (Au) nanoparticles and CNT-Au nanoparticle heterostructures. Encapsulation of Au nanoparticle with a multilayer graphene shell in GNPs did not suppress optical properties and surface plasmons of the former. Tunable optical characteristics of GNPs were calculated that showed resonance peak wavelengths, corresponding to encapsulated Au nanoparticle, between ∼527 and ∼663 nm as a function of size and multilayer graphene shell thickness. Enhanced optical/plasmonic behavior and intense 'hot spots' were estimated for CNT coated with tightly-packed GNPs as compared to CNT coated with bare Au nanoparticles.