Electrochemical fabrication of oriented ZnO nanorods on TiO_{2 nanotubes

We report the ability to use TiO2 nanotube as a guide layer to achieve the vertical growth of ZnO nanorods, in additive–free bath. First, we focused on the anodisation conditions (cell voltage and anodisation time) to produce TiO2 nanotube thin films grown from a 1.5 µm thick Ti layer sputtered onto Si. Highly organised titania nanotubes were obtained in glycerol viscous electrolyte. In a second step, the electrochemical growth of ZnO grains has been investigated from a zinc nitrate bath at 70°C on both Ti foil and TiO2 nanotubes. ZnO deposition mechanism has been highlighted through the electrochemical experiments in conjunction with XRD technique and scanning electron microscopy (SEM) examinations. On Ti foils, we show that addition of additives is required to obtain a highly oriented nanostructured ZnO deposit. On TiO2 nanotubes, additives are not necessary to obtain such a deposit: Titania nanotubes can be used to guide the vertical growth of hybrid nanoarchitectured ZnO/TiO2 electrode.