Growth Mechanism and Functional Properties of Gas-Phase Synthesized Few-Layer Graphene

Abstract

Microwave plasma-based gas-phase synthesis of graphene and its derivatives represents a simple, environmentally friendly, and easily scalable production method enabling emerging large-scale applications. Microwave plasma decomposition of organic precursors, hydrocarbons, and alcohols, forms a hightemperature environment, where the process of catalyst-free dehydrogenation and consequent formation C atoms and C2 molecules leads to the nucleation and growth of high-quality few-layer graphene nanosheets. Structure of the synthesized carbon material changed from graphitic nanoparticles to graphene nanosheets with increasing H/C atomic ratio in the precursors, for C2H2 and CH4, respectively. Using alcohols, ethanol -C2H5OH and diethylether -(C2H5)2O, the main hydrocarbon fragments generated during the decomposition of CxHyO structure resulted in the gas composition with high enough H/C atomic ratio to growth nanosheets with low intensity Raman D band and high integrated intensity ratio of 2D/G Raman band, 1.5 and higher. However, the yield of the synthesis strongly depended on the arrangement of atoms in the precursor molecule. Prepared material was analyzed by electron microscopy, Raman and X-ray photoelectron spectroscopy and thermogravimetry. High temperature oxidation resistance and electrical conductivity of prepared samples was investigated.