A facile method for preparing a non-adhesive superhydrophobic ZnO nanorod surface

To prepare a non-adhesive superhydrophobic ZnO nanorod surface, ZnO nanorods have been grown on Si substrates by using a two-step hydrothermal process. The first and secondary growths preferentially orient along the c-axis. By increasing the secondary growth time, the ZnO nanorods grow longer. However, above a certain level, on further increasing the secondary growth time, the nanorod length, width, and orientation show obvious polydispersity and some nanorods emerge from others. After modification with stearic acid, length and homogeneity of the nanorod control the wetting state of the surface. The surface of the longest and homogeneous ZnO nanorods obtained after secondary growth shows a stable superhydrophobicity with the very low contact angle hysteresis. (C) 2012 Elsevier B.V. All rights reserved.