A General Approach for the Growth of Metal Oxide Nanorod Arrays on Graphene Sheets and Their Applications

In the fabrication of flexible devices, highly ordered nanoscale texturing, such as semiconductor metal oxide nanorod arrays on flexible substrates, is critical for optimal performance. Use of transparent conducting films, metallic films, and polymer substrates is limited by mechanical brittleness, chemical and thermal instability, or low electrical conductivity, low melting point, and so on. A simple and general nanocrystal-seed-directed hydrothermal route has now been developed for large-scale growth of nanorod arrays of various semiconductor metal oxides (MO), including TiO2, ZnO, MnO2, CuO, and ZrO2 on both sides of flexible graphene (G) sheets to form sandwichlike MO/G/MO heterostructures. The TiO2/G/TiO2 heterostructures have much higher photocatalytic activity than TiO2 nanorods, with a photocatalytic degradation rate of methylene blue that is four times faster than that of the TiO2 nanorods, and are thus promising candidates for photocatalytic decontamination.