Controllable preparation and photocatalytic activity of highly ordered ZnO nanoarrays

Abstract

Well-aligned ZnO nanotubular arrays (NTs) and nano rod-like arrays (NRs) were controllably fabricated on glass substrates through a facile hydrothermal method, and the prepared ZnO nanoarrays could be easily retrieved in the photodegradation of organic pollutants because ZnO is “growing” on the substrates. The morphology of ZnO nanoarrays could be governed by the cooling process and reaction time during the preparation. ZnO NTs tend to be formed by natural cooling, while ZnO NRs are apt to be constructed by sudden cooling. Furthermore, with the proceeding of the reaction, the ZnO nanoarrays display headless-pyramid configuration gradually. The ZnO nanoarrays prepared at 90 oC for 4 h show excellent photocatalytic activity. In the presence of the prepared ZnO NTs and NRs, the degradation rate of methylene blue (MB) is up to 96.8% and 94.1% after 1 h UV irradiation, respectively. The better photocatalytic performance of ZnO NTs is ascribed to the highly ordered array and large specific surface area which could promote the transfer of photo-generated electrons and restrain the recombination of electron-hole pairs. The well-aligned ZnO nanoarrays in this study could be fabricated on different substrates. Moreover, they could potentially serve as excellent photocatalysts in waste water treatment.