Controlled growth of ZnO nanorod templates and TiO2 nanotube arrays by using porous TiO2 film as mask

Porous TiO2 thin films obtained from sol–gel self-organize approach were firstly used as masks to control the growth of ZnO nanorod arrays by aqueous solution method. The effect of TiO2 pore size on the density of ZnO nanorod arrays was investigated by atomic force microscopy and field emission scanning electron microscope. The results show that the density of ZnO nanorod arrays obviously decreases after using porous TiO2 masks, and increases with increasing the TiO2 pore size. Additionally, the existence of TiO2 mask can also effectively prolong the wet-chemical etching time of TiO2 nanotube arrays manufactured from ZnO nanorod templates assisted sol–gel method, to completely remove the ZnO nanorod templates and to avoid collapsing of TiO2 nanotube arrays from the substrates.