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

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 degrees 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.