Sunlight-active hierarchical Ag@insulator@ZnO core-shell array based on natural diatoms for environmental remediation

•Siliceous diatom frustules were used to fabricate hierarchical plasmonic-based ZnO.•The regular structure of frustules were in favor of uniform metal and semiconductor assembly.•The synergistic effect of metal/insulator/semiconductor improved photocatalysis action under sunlight irradiation.•Significantly higher performance was achieved compared to the pristine counterparts.