Fabrication of through-hole TiO₂ nanotubes by potential shock

Through-hole nanotubular membranes of anodic TiO₂ were successfully prepared through the removal of the barrier layer using potential shock. The abrupt increase in the potential at the end of the anodization allowed the pores to homogenously open in the barrier layer within 10 s. The pore opening corresponded to the breakdown of the center of the barrier layer through the massive diffusion of the F^- ions, which were triggered by the significantly high potential (here, > 80 V). The potential shock voltage and time were optimized based on the breakdown mechanism. This method is immediately applicable for preparing the through-hole membranes of anodic TiO₂ because it rapidly produces homogenous pore openings without the need for any complicated processes or dangerous chemicals.