Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications

Orderly aligned ZnO nanorods grown on various substrates via a facile one-step and catalysts/seed-free hydrothermal route exhibited superior photocatalytic activity for decomposing methyl orange and excellent sensing performance towards flammable gases, suggesting their potential applications in environmental remediation and monitoring. [Display omitted] ► Orderly aligned ZnO nanorods can be grown on various substrates without catalysts and seeds through a simple one-step hydrothermal route. ► The prepared ZnO nanostructures exhibited superior photocatalytic activity for decomposing Methyl orange. ► The obtained ZnO nanostructures exhibited excellent sensing performance towards some flammable gases. A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response–recovery characteristics, good selectivity and long-term stability.