Controllable fabrication of three-dimensional radial ZnO Nanowire/silicon microrod hybrid architectures

A facile method by combining bottom-up and top-down approaches was developed to construct uniform three-dimensional (3D) ZnO nanowires (NWs)/silicon microrod (SiMR) hybrid architectures. Patterned SiMR arrays with controlled geometry and density were structured by photolithography and chemical etching on single-crystal silicon wafers, which subsequently served as 3D scaffolds for the ZnO NW growth. In contrast to the top-down approach to fabricate SiMR scaffolds, the radial ZnO NWs grown conformally on the SiMRs follow a bottom-up method by employing a modified carbon-assisted self-catalytic growth via chemical vapor deposition. The light absorption and the photocatalytic capability of methyl red of ZnO NW arrays were demonstrated to improve significantly by the 3D constructions. The method is expected to be applicable to the synthesis of 3D hybrid structures of other nanomaterials. The heterojunction and ultralarge surface area of the 3D architectures are promising for diverse applications in photovoltaics, catalysts, and sensing. © 2010 American Chemical Society.