Graphene/Single-Walled Carbon Nanotube Composites Generated by Covalent Cross-Linking

Composites of graphene and single-walled carbon nanotubes (SWNT) have been generated by covalent cross-linking through two different coupling strategies, namely Sonogashira and EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) coupling reactions. The obtained assemblies have been characterized by various microscopic and spectroscopic techniques. The assemblies obtained by Sonogashira coupling exhibit high surface area, the value increasing with the graphene content. The highest surface area obtained is 1260 m(2) g(-1) in the composition with highest graphene content (graphene:SWNT 1:4). These composites show a uniform slit-shaped porous network with pores of approximately 1-2 nm. CO2 uptake of this assemblies is in the range 11-15 wt % at 273 K (1 atm) and 9-11 wt % at 298 K (1 atm), whereas the H2 uptake is in the 1-1.3 wt % range at 77 K (1 atm). The composites generated by Sonogashira coupling show superhydrophobicity with high contact angles in the range from 159-163°. The EDC-coupled composites show less surface area than the composites from Sonogashira coupling.