Architecture of tunable three-dimensional graphene assembly with unique plasmonic properties

Abstract

Besides two dimensional (2D) graphene sheets which show superior electrical, thermal, and mechanical proper-ties, three dimensional (3D) graphene assembly also recently garnered great attention due to its high surface area, flexible and free-standing configuration, and facile fabrication of the graphene composite with nanomaterials in practical graphene applications. However, to date, the morphology of the 3D graphene structure has been limited to spherical shape. Herein, we demonstrated the synthesis of a variety of 3D graphene assembly including sphere, twiddle, and hemisphere. Such 3D reduced graphene oxide (rGO) structures could be manipulated by controlling the aggregation pattern of the GO sheet inside the micro-droplets. The aggregation pattern depended on the diffu-sion rate of the droplet solvent that were simply tuned by the amount of an oil phase. In addition to the fabrica-tion of the versatile 3D graphene materials, their micro-porous structure was manufactured by compositing silica beads in the rGO microparticles followed by a wet etching process. Noticeably, the 3D porous hemispherical rGO revealed unique surface plasmonic characteristics similar to the single layered graphene as well as a bulk plasmon effect, which were confirmed by an electron energy-loss spectroscopy (EELS) mapping. These results are the first-time demonstration showing the plasmonic properties of the 3D graphene structure which can expand the application arena of the 3D graphene materials.