The simultaneous epitaxial growth of vertical nanorod arrays and thin films of zinc oxide (ZnO) was realized on a gold-plated plane sapphire substrate via a simple chemical vapor deposition method. In this nanostructure, the vertical single crystal nanorods are hexagonal prism or cylindrical in shape, and are all grown on a ZnO thin film, so that the vertical nanorods are connected to each other through the beneath thin oxide ZnO film. In comparison with ZnO nanofilms, the prepared nanostructure has excellent photoelectrochemistry (PEC) performance with an incident photocurrent efficiency of 2.4 times that of the simple ZnO nanofilms; while its light energy conversion efficiency is 5 times that of ZnO nanofilms. Its excellent PEC performance can be attributed to its high surface area-to-volume ratio and the carrier transport channel provided by the supporter ZnO film. The mechanism for cooperative growth of ZnO nanorod arrays and thin films was proposed as follows: during the processing, Au liquefies and absorbs Zn atoms in the atmosphere forming alloys. After the alloy droplets were supersaturated ZnO begins to nucleate, and then ZnO film formed on the surface of the substrate. At the same time, Zn autocatalyzed (vapor-solid)VS growth and Au catalyzed (vapor-liquid-solid)VLS growth occurred, respectively forming hexagonal prism nanorods and cylindrical nanorods, and finally a vertical nanorod array was connected through the underneath thin ZnO film.

Keywords： inorganic non-metallic materials; ZnO nanorod arrays; simultaneous epitaxy; PEC