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.