Model studies of SOCl2 adsorption on carbon nanotubes

The experimentally observed oxygen content increase in SOCl2 treated single-wall carbon nanotubes (SWCNTs) may be explained by the air moisture hydrolysis of the acid-chloride groups created at the structure defects as well as of SOCl2 molecules adsorbed at SWCNT sidewalls. The first step of this process, thionylchloride adsorption on pyrene C16H10 and coronene C24H12 as simple models of the graphene sheet, has been studied at B3LYP/6-31+G** level of theory. The pyrene molecule is too small to be a suitable model for SOCl2 adsorption. Non-planar thionylchloride molecules are physisorbed preferably with sulphur atoms oriented to the carbon sheet with high affinity to the structure defects (edges). The SOCl2 physisorption supports the metallic character of graphene sheets.