Preparation And Photoelectrochemical Properties Of Titanium Dioxide Nanotube Films And Self-doped Materials

Since Zwillng et al.has reported the growth of TiO₂ nanotube arrays（TNTs）by a simple anodization method in 1999,TNTs have attracted much attention from researchers in many fields.Compared with TiO₂films,TiO₂ with nanotube structures has a good light confinement effect,one-dimensional transport direction,high surface-to-volume ratios,as well as unique optical and electrical properties.Thus,it has been widely used in many fields such as sensors,solar cells,photocatalysis,biomedicine,and micro-electronic devices.Firstly,based on the influence of the substrate and morphology of TNTs on the performance of TNTs-based micro-electronic devices,the fast growth of highly ordered TNTs on different functional substrates has become a hot research issue.Although the technique of preparing TNTs thin film on Ti substrate has been significantly improved,obtaining high quality TNTs on other functional substrates（such as silicon substrate,conducting glass subs trate etc.）with high efficiency is still challenging.In our work,we have prepared TNTs with high quality and controllable morphology by high field anodization method,and systematically investigated the effect of anodization parameters（anodization time,applied voltage,and electrolyte concentration）on the morphology and growth rate of TNTs.More importantly,combining the current density-time plots recorded over the whole anodization process can provide a facile way to determine the optimal anodization condition.This work is anticipated to provide a method to fabricate other metal oxide nanotubes on different functional substrates.In the next work,we have prepared Ti³⁺self-doped TNTs by combining high field anodization and electrochemical reduction method.By controlling the electrochemical reduction duration and potential,both Ti³⁺concentration and its photoelectrochemical（PEC）performance can be optimized.Under the optimum parameter,a high photocurrent density of⁰.525 mA cm^-2 was obtained,which is nearly 3.1 times that of pristine TNTs.By combining the diverse characterization techniques,electrochemical impedance spectra and Mott-Schottky plots,a possible explanation for the enhanced PEC performance can be proposed.