As some of the most interesting metal-free catalysts, carbon nanotubes (CNTs) and other carbon-based nanomaterials show great promise for some important chemical reactions, such as the selective oxidation of cyclohexane (C H ). Due to the lack of fundamental understanding of carbon catalysis in liquid-phase reactions, we have sought to unravel the role of CNTs in the catalytic oxidation of C H through a combination of kinetic analysis, in situ spectroscopy, and density functional theory. The catalytic effect of CNTs originates from a weak interaction between radicals and their graphene skeletons, which confines the radicals around their surfaces. This, in turn, enhances the electron-transfer catalysis of peroxides to yield the corresponding alcohol and ketone. Cyclohexane oxidation over nanotubes: A weak interaction between radicals and graphene skeletons significantly promotes the catalytic oxidation of cyclohexane by confining the radicals around the surfaces of CNTs (see scheme). This, in turn, enhances the electron-transfer catalysis of peroxides to yield the corresponding alcohol and ketone. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.