Enhancement in photocatalytic activity and biological properties of Sm doped ZnO nanostructures by the increase in Sm contents

•The sol–gel approach was used to produce undoped and Sm-doped ZnO nanostructures by using Sm 6–10 wt%.•The size of the crystallites was enhanced as the Sm content was increased.•9 wt% Sm in ZnO has shown the best photocatalytic performance.•Sm doped ZnO nanostructures are effective against all selected bacterial strains.•These nanocrystals would break down bacterial and chemical pollutants in water in the sunshine.