Preparation and Electrochemical Properties of Flow-Through TiO<sub>2</sub> Nanoarray
Yi Xie
Abstract
Microstructure-tailored TiO 2 nanoarrays with adjustive wall-hole morphology have been designed to improve electrochemical properties. Tubular, porous and flow-through TiO 2 nanoarrays are fabricated by one-stepped, two-stepped and three-stepped anodization process under the controlled reaction condition. Tubular nanoarray with the opened-mouth and closed-bottom has a tube diameter of 120-130nm, a length of 8.12μm, and wall thickness of 15nm. Similarly, porous TiO 2 nanoarray with the opened-mouth and closed-bottom has a pore diameter of 60-70nm, a length of 8.25μm, neighboring wall distance of 70-80nm. Comparatively, flow-through TiO 2 nanoarray with the opened-mouth and opened-bottom has a pore diameter of 110-120nm, a length of 8.56μm, neighboring wall distance of 40nm. In comparison with tubular and porous TiO 2 nanoarrays, flow-through TiO 2 nanoarray indicates the deceased charge transfer resistance and diffusion-related Warburg impedance, presenting the enhanced current response at the same electrode potential. Accordingly, bottom-opened flow-through TiO 2 nanoarray achieves the specific capacitance of 6.35 mF cm -2 , which is higher than the bottom-closed tubular and porous TiO 2 nanoarrays (2.94 and 3.78 mF cm -2 ). The flow-through TiO 2 nanoarray presents the improved electrochemical performance for the electrochemical energy-storage.