Preparation of superhydrophobic ZnO films on zinc substrate by chemical solution method

Superhydrophobic surface was prepared on the zinc substrate by chemical solution method via immersing clean pure zinc substrate into a water solution of zinc nitrate hexahydrate[Zn(NO ₃) ₂·6H ₂O] and hexamethylenetetraamine(C ₆H ₁₂N ₄) at 95 ^oC in water bath for 1.5 h, then modified with 18 alkanethiol. The best resulting surface shows superhydrophobic properties with a water contact angle of about 158 ^o and a low water roll-off angle of around 3 ^o. The prepared samples were characterized by powder X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy(EDX), transmission electron microscopy(TEM), and scanning electron microscopy(SEM). SEM images of the films show that the resulting surface exhibits flower-shaped micro- and nano-structure. The surfaces of the prepared films were composed of ZnO nanorods which were wurtzite structure. The special flower-like micro- and nano-structure along with the low surface energy leads to the surface superhydrophobicity.