Evaluation of structural features of crystalline and amorphous Ta₂O₅ NTs by X-ray Spectroscopy: Effects of structural disorder on the photocatalytic activity

Full text: Recently the electrochemical anodization for the manufacturing of high ordered and self-organized semiconductors with nanotubular (NTs) structures has attracted great scientific interest. The main advantages of the anodization encompass a simple synthetic procedure, a cost-effective scale-up process and an art to control the structures sizes as well as their charge transport properties. Because of its wide range of applications and potential chemical, electrical, electronic, biocompatible and optical properties the Ta₂O₅ nanostructures have been extensively studied both experimentally and theoretically over the past three decades. The as-anodized Ta₂O₅ NTs are usually amorphous and heat treatment is often performed to convert the amorphous phase to crystalline phase. However, it has been shown that the heat treatment parameters affect the crystalline structure and morphology of semiconductor NTs. Furthermore, for many technological applications such as photocatalysis (water splitting) and solar cell (Gr¨atzel solar cell) the crystallinity of the semiconductor nanotubes has a vital effect. In this work, we choose the EXAFS and XANES techniques to evaluate the electronic structure and structural disorder of the Ta₂O₅ NTs. The results will be correlated to the photocatalytic activity for hydrogen production by the reaction of water splitting. (author)