Decoration of graphene sheets with silver nanoparticles and their characterization

Abstract

Graphene has been an emerging area of research since last decade. This fantastic material promises a wide variety of applications starting from electronics to biomedical fields. The properties of graphene can be enhanced by conjugating it with various other elements. The present work describes about the deposition of silver nano-particles via chemical synthesis onto in-house synthesized graphene nanosheets. It can be pointed out that application of infrared accelerates the synthesis process. Few layered graphene nanosheets (FLGNs) has been synthesized through electrochemical exfoliation technique. The colloidal graphene solution stabilized by citrate ions helps in the chemical reduction of AgNO3, which is essential in the formation of a nano-sized silver particulate layer (Ag NPs) over the graphene sheets. The presence of Ag NPs over the as-synthesized graphene was established by XRD, UV–VIS, FE-SEM and STM studies. The change in colloidal stability for the as-synthesized graphene and Ag NPs coated graphene was explained by the dynamic light scattering studies. The electronic characteristics of graphene coated Ag NPs was studied by scanning tunneling spectroscopy (STS) technique. The STS studies revealed that graphene with various numbers of coupled layers is responsible for the variations in the density of states (DOS) pattern. For Ag NPs-FLGNs, the spatial variations in the DOS spectra can be correlated to the size effects of the Ag NPs over the FLGNs. The local density of states (LDOS) spectra originates from the quantized electronic structure of the Ag NPs–FLGs system.