A Low Temperature, Liquid Phase Route to Porous Graphene and Graphene-Magnetic Composites

Nanocarbon allotropes and their composites with transition metal oxides are a promising class of materials possessing vast surface area, high electrical conductivity, and corrosion resistance. Here we report a novel, liquid-phase synthesis of graphene-coated metal oxide nanocrystals which yields from one to ten graphene layers (T ≤390 °C) in nonpolar organic solvents. The process begins with the thermal decomposition of a metal carboxylate to generate CO and/or CH₄ which then become the carbon feedstock for the growth of high quality graphene templated onto iron oxide nanoparticles. By varying the reaction temperature, the carboxylate decomposition rates can be controlled to form nanoscale graphene films with tunable thickness up to 3 nm. These films can be extracted from the metal oxide substrate by acid etching to obtain graphene nanoflakes or porous graphene. Alternatively the graphene-iron oxide composites can be assembled into conductive and magnetic films useful for electrocatalysis and electrochemical sensing.