Microwave-assisted preparation of Zn1−xCuxS nanoparticles by a fast, green, and template-free method and photocatalytic activity

► A microwave-assisted method was applied for preparation of Zn1−xCuxS nanoparticles. ► The Cu2+ ions are homogeneously substituted for Zn2+ ions in the ZnS lattice. ► Photocatalytic activity was investigated under visible light irradiation. ► Nanoparticles of Zn0.97Cu0.03S exhibit highest photocatalytic activity. ► The rate constant decreases with microwave irradiation time.