▎ 摘　　要

Despite extensive development efforts on new catalysts for cyclohexane oxidation, current commercial processes are still desirable to further decrease the economic and environmental costs in the oxidation procedures. In this study, the catalyst properties of metal-free functionalized graphene oxide (GO) in the selective oxidation of cyclohexane is investigated to understand the effects of structure, functional groups and oxygen-containing groups. Both GO sheets and nano graphene oxide (NGO) sheets possess high cyclohexane conversions of 16.7% and 17.7% comparable to that of metal catalysts in the aerobic oxidation of cyclohexane. The higher catalytic activity of NGO sheets is caused by the smaller size and the higher content of -COOH. Within the oxygen-containing groups, the carboxylic acid groups on the surfaces of GO are supposed as the active site for the generation of center dot O-2(-) radical, which is the active oxygen species in this catalytic oxidation process. (C) 2017 Elsevier B.V. All rights reserved.