Mechanism for wettability alteration of ZnO nanorod arrays via thermal annealing in vacuum and air

▸ Oxygen vacancy is the key factor in accounting for the change in morphology of the ZnO nanorod arrays. ▸ We firstly investigated the wettability alteration of ZnO nanorod arrays annealed in vacuum at different temperature. ▸ The hydrophilicity of the ZnO nanorod arrays annealed in air is not related to the oxygen vacancy but ascribed to the O adatom on the nanorod surface.