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Cu 2 O/CuO composite thin films were synthesized by a facile hydrothermal method on Cu foils. Surface morphology, chemical composition, microstructure and wettability were investigated by scanning electron microscope, X-ray photoelectron spectroscopy, X-ray diffractometer and water contact angle apparatus. The results indicate that the Sample 2 is composed of many regular Cu 2 O octahedrons, tiny nanovillus and a small amount of spheric particles. The other samples were composed mainly of flower-like microparticles and regular Cu 2 O octahedrons. The content of copper (II) increases firstly and then decreases and the maximal value of content of copper (II) has been observed in the Sample 2. The Sample 2 displayed superhydrophobic property owing to its hierarchical porous micro/nanostructured surface.

ZnO thin films have been synthesized by means of a simple hydrothermal method with different solvents. The effect of deionized water content in the mixed solvents on the surface morphology, crystal structure, and optical property has been investigated by scanning electron microscopy, X-ray diffraction, and UV-Vis spectrophotometer. A large number of compact and well-aligned hexagonal ZnO nanorods and the maximal texture coefficient have been observed in the thin film, which is grown in the mixed solvent with x = 40%. A lot of sparse, diagonal, and pointed nanorods can be seen in the ZnO thin film, which is grown in the 40-mL DI water solution. The optical band gap decreases firstly and then increases with the increase of x. Reversible wettability of ZnO thin films were studied by home-made water contact angle apparatus. Reversible transition between hydrophobicity and hydrophilicity may be attributed to the change of surface chemical composition, surface roughness and the proportion of nonpolar planes on the surface of ZnO thin films. Photocurrent response of ZnO thin films grown at different solvents were measured in air. The response duration of the thin film, which is grown in the solvent with x = 40%, exhibits a fast growth in the beginning but cannot approach the saturate current value within 100 s. The theoretical mechanism for the slower growth or decay duration of the photocurrent has been discussed in detail.

The microstructure, surface topography and wetting properties of zinc oxide (ZnO) thin films, which were grown at different concentrations of zinc nitrate hexahydrate, were measured by x-ray diffractometry, scanning electron microscopy and water contact angle apparatus. It is revealed that at concentrations larger than 0.01 mol l−1, one peak corresponds to the (111) direction of the cubic phase of ZnO, except for six peaks of the hexagonal phase of ZnO, was observed. As the concentration increases, the average diameter and density of the ZnO nanorods increase but the area proportion of the nonpolar planes in the outermost surface increase first, then decrease. All the ZnO thin films exhibit hydrophobic behavior. After 120 min of ultraviolet irradiation, the wettability of the ZnO surfaces change from hydrophobicity to hydrophilicity. The photo-induced change of the water contact angle increases first then decreases with the increase of concentration. The differences of photo-induced hydrophilicity may be determined by the transition of the wetting model, the area proportion of the nonpolar planes and the surface roughness.