Anodic TIO₂: Fabrication, current applications and future perspectives

Although nanostructured alumina was successfully fabricated by electrochemical anodization decades ago, it is only until recently that the electrochemically anodized TiO2begins to attract more and more research interest and is now becoming an emerging area of a wide range of important applications, such as, gas sensing, self cleaning, antifogging, water purification, anticorrosion, solar cell, lithium batteries, electrochemical supercapacitors, photo cleavage of water, antibacterial coating, and the improvement of biocompatibility, etc. This is due fundamentally to the fact that TiO2is a semiconductor with reactivity or photoreactivity closely related to its defect structure. A variety of attractive functional properties of TiO2are the result of its unique electronic band structure which can also be easily tuned by defects. In this article we will give a detailed review on recent progress in the fabrication of anodic TiO2nanostructure, the control of its morphology by varying anodization conditions, and the microstructure related properties. We will also review the recent research efforts in various practical applications of anodic TiO2with dopants or modifications. Potential future applications of anodic TiO2with highly ordered nanostructures are also suggested.