We report on the photocatalytic performance of the ZnO:Co + Ag nanocomposite photocatalyst coupled with the commercial cyanic blue Sr4Al14O25 : Eu,Dy long afterglow phosphor. In this composition the phosphor can harvest and recover light as persistent phosphorescence. The contribution of the phosphor to the photocatalytic model reaction of methyl orange dye decomposition in aqueous solution was experimentally verified under power-saving illumination conditions. The two most important findings of this work are that the cobalt doped and silver nanoparticle decorated ZnO nanocomposite catalyst can outperform bulk ZnO under certain conditions and that rare earth metal doped strontium aluminate phosphor assistance allows running photocatalytic experiments with short on/long off illumination pulses. Power savings over one order of magnitude are possible this way while maintaining a photocatalytic performance comparable with that achieved using continuous illumination. This suggests a strategy to design new arrangements of more sustainable photocatalytic reactors and catalyst compositions for effective treatment of wastewaters or air pollutants. (C) 2016 Elsevier B.V. All rights reserved.