Graphene synthesis by top-down and bottom-up strategies

Abstract

Graphene is a two-dimensional structure arranged in a hexagonal form (similar to a honeycomb) that has unique physicochemical properties and has generated interest in the scientific community for its properties and applications. To produce graphene, several methods are used, all of them can be divided in two approaches: the bottom-up approach and top-down approaches. In this work, both routes will be explored. In the bottom-up approach, the properties of graphene over a mono crystalline nickel surface obtained by chemical vapor deposition (CVD) will be studied. In the top-down approach, natural graphite will be used to construct graphene based materials with innovative approaches. Obtained products are characterized by Auger electron spectroscopy, Low energy electron diffraction, Scanning (SEM)and transmission (TEM) electron microscopy, Raman spectroscopy , X-ray photoelectron spectroscopy (XPS) and Energy electron loss spectroscopy (EELS). As a result, in the bottom-up approach, Cesium restored the linearity of the graphene and it behaved as a free-standing graphene, when is well known that exist a strong interaction between graphene and the metal substrate. In the top-down approach, graphene oxide free-defect layers that are very large and transparent were obtained. Preparated layers chemically seem to coordinate zeolite crystals probably to obtain the necessary energetic stabilization.