Surface studies of hydroxylated multi-wall carbon nanotubes

► The surface oxygen levels of MWCNTs have been increased from 4.3 to 22.3 at.% using the Fenton hydroxylation reaction. ► No significant structural disruption to the MWCNTs is detected but their surface chemical properties are significantly improved. ► The hydroxylated materials have an enthalpy of immersion in water of −193 mJ m−2, this gives enhanced water wettability and dispersion. ► Water vapour adsorption, which occurs by hydrogen bonding at polar surface oxygen groups, is also increased. ► Using graphitized MWCNTs evidence supporting direct attack at the graphene ring as one possible hydroxylation mechanism is presented.