Abstract

In the flexible devices' fabrication, highly ordered nanoscale texturing such as semiconductor metal oxide nanorod arrays on the flexible substrates is critical for optimal performance. Herein, a simple and general hydrothermal route has been developed to result in a large-scale growth of ZnO nanorod arrays on double sides of the flexible reduced graphene sheets (rGss) forming sandwichlike heterostructures of ZnO/G/ZnO, and on a single side of the flexible rGss forming two-layered heterostructures of ZnO/G. The diameter and density of the ZnO nanorods grown on the rGss can be easily tuned as required by varying the seed-solution concentration. Due to the outstanding mechanical and electrical properties of the rGss, two-layered ZnO/G heterostructures were demonstrated to possess excellent field emission properties (turn-on field as low as 2.1 V μm−1, the emitting current ∼470 μA cm−2 at 3 V μm−1) and gas sensing (three times the ZnO nanorods); the sandwichlike ZnO/G/ZnO heterostructures have much higher photocatalytic activity under UV irradiation than those of ZnO nanorods and ZnO/G heterostructures, suggesting a promising candidate for photocatalytic decontamination. This would open up possibilities for the extensive study of the physical and chemical properties from these most promising nanostructures and extend their practical applications.