In this study, we synthesized Cu2O particles with rough surfaces by a facile solvothermal method as a dual-function material that can degrade contaminants not only under light irradiation but also in dark circumstance. Both the as-prepared Cu2O and commercial Cu2O exhibited excellent performance for the removal of methyl orange under visible light irradiation through a photocatalysis-based strategy. However, the former was found to show remarkable capability under dark circumstances by means of molecular oxygen activation, while the latter performed poor efficiently under the same condition. This significant difference of performances under dark circumstances was related to rich oxygen vacancies existed on the as-prepared Cu2O surfaces that are associated with the single-electron reduction of O-2 to generate O-center dot(2), which play a dominant role in the generation of Cu+. In addition, Cu+ was identified to play key roles in the broken of azo bond. Then, the generated intermediates were mineralized by (OH)-O-center dot generated through molecular oxygen activation process. This study could not only deep the understanding of the MO removal mechanism by Cu2O but also show a novel direction of amphibious application for photocatalytic materials. (C) 2018 Elsevier B.V. All rights reserved.