Two-step growth of superhydrophobic ZnO nanorod array films

Well-aligned ZnO nanorod array films (ZnO-NAFs) were coated on common glass substrate by two-step method. A thin buffer layer of ZnO seeds were first deposited via RF magnetron sputtering, the ZnO-NAFS were then grown in a simple aqueous solution. We report a surface-modification induced hydrophilicity to superhydrophobicity transiton on ZnO-NAFs. The sample was characterized by scanning electron microscopy (SEM). The surfaces of ZnO-NAFs was superhydrophobic with a three-phase contact angle of 151 degrees +/- 0.5 degrees, while the sliding angle is 7 degrees. The superhydrophobicity of ZnO-NAFs was validated by Cassie's model.