Supported cobalt oxide on graphene oxide: Highly efficient catalysts for the removal of Orange II from water

► Cobalt oxide supported on graphene oxide (GO) in a solvothermal system. ► The structure of the Co3O4/GO catalyst is stable and the well-dispersed Co3O4 particles on GO. ► The Co3O4/GO catalyst is an efficient heterogeneous catalyst for activation of PMS. ► The Co3O4/GO/PMS system is able to completely degrade Orange II within a very short duration of a few minutes. ► Very limited cobalt dissolved from Co3O4/GO.