Superhydrophilic zinc oxide film prepared by controlling ZnO microrods growth and its attractive recyclable photocatalytic performance

•Superhydrophilic ZnO microrod films were successfully synthesized.•ZnO microrods are single crystalline with the hexagonal wurtzite structure.•ZnO microrod films can be easily separated from the solution.•Superhydrophilic ZnO microrod films can be reused.

Superhydrophilic functional materials have been found to be of great value for a variety of practical applications in recent years. In this paper, zinc oxide (ZnO) microrod films have been directly synthesized on a large-area zinc substrate via a simple solution method. Morphological and structural observation and crystallinity of the grown products were carried out using scanning electron microscopy, X-ray diffraction, energy dispersive spectrometer, transmission electron microscopy, ultraviolet (UV)–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The influence of reaction time on the size and shapes of the as-prepared ZnO samples was studied. It was found that superhydrophilic ZnO films at reaction time of 20 h were made up of uniform pure ZnO microrods with 600 nm in average diameter and 6 μm in length. Room-temperature PL spectra of the ZnO products showed a UV emission and a broad green band. Photocatalytic performance and sample stability were studied. Under UV light irradiation over 95% of methylene blue was degraded by ZnO microrod films in 4 h, ZnO microrod film can be easily separated from the solution, and no observable performance degradation was observed after 5 cycles.