Reversible Super-hydrophobicity to Super-hydrophilicity Transition of Aligned ZnO Nanorod Films

Abstract

Remarkable surface wettability transition occurs with an inducement of ultraviolet (UV) for aligned ZnO nanorod films. The inorganic oxide films, which show super-hydrophobicity (left), become super-hydrophilic (right) when exposed to UV illumination. After the films are placed in the dark, the wettability evolves back to super-hydrophobicity. This reversible effect is ascribed to the cooperation of the surface photosensitivity and the aligned nanostructure. Such special property will greatly extend the applications of ZnO films.