ZnO nanowire thin film was synthesized in situ on patterned Zn substrate via a simple and seed-free hydrothermal method. The as-synthesized products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion X-ray analysis(EDS), UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), and photoluminescence (PL) spectroscopy. The time-, temperature- and ammonia concentration-dependent morphology evolution were observed. The results showed that the Zn MPs, in the presence of the reaction solution, can be gradually dissolved, thus providing the Zn source for successive nucleation and growth of ZnO nanowires. The increase of the light absorption as well as a red shift of the band edge was related to the increase of the quantity and the defects of ZnO nanowires. A growth mechanism was proposed to understand the formation of ZnO nanowires on the plated Zn substrate. Under UV irradiation, the as-synthesized ZnO nanowire film exhibited good photocatalytic activity and high photochemistry stability in a wide pH range of 5-10. Furthermore, the ZnO nanowire film can be easily separated, demonstrating great potential for practical application in the degradation of the organic pollutant while exhibiting high reusability. (C) 2015 Elsevier B.V. All rights reserved.