Phase transformation of TiO2 nanobelts and TiO2(B)/anatase interface heterostructure nanobelts with enhanced photocatalytic activity

Abstract

TiO₂ nanobelts are very attractive due to their dimensional confinement and structurally well-defined physical and chemical properties. However, the obscure phase transformation mechanism and the low photocatalytic activity of TiO₂ nanobelts limit their wide applications. Here, the phase transformations among H₂Ti₃O₇, TiO₂(B), anatase and rutile nanobelts were characterized in detail by X-ray powder diffraction, high resolution transmission electron microscopy, Raman spectroscopy and UV-Vis diffuse reflectance spectra. TiO₂(B) is inevitable in the phase transformation of TiO₂ nanobelts due to the shape limiting effort and the similar crystal structure between H₂Ti₃O₇ and TiO₂(B). TiO₂ nanobelts have a good thermal stability for the crystal phase and nanostructures. TiO₂(B)/anatase interface heterostructure nanobelts were obtained by calcining H₂Ti₃O₇ nanobelts at 800 °C, which had an enhanced photocatalytic ability comparing with pure TiO₂(B) and anatase nanobelts. The mechanisms of the phase transformation of TiO₂ nanobelts and the enhanced photocatalytic activity of TiO₂(B)/anatase interface heterostructure nanobelts were discussed. The self-transformed heterostructure nanobelts have good photocatalytic activity, stability and easy-recovery properties, which will have important practical applications.