Effects of additives on microstructures of titanate based nanotubes prepared by the hydrothermal process

Silica-containing TiO2-derived titanate nanotubes were prepared by the addition of a small amount of tetraethyl orthosilicate (TEOS) to TiO2-derived titanate nanotubes prepared by the hydrothermal process and a subsequent heat-treatment at 473 K in air. The microstructure and thermal behavior of synthesized silica containing TiO2-derived titanate nanotubes were investigated by various methods such as X-ray diffraction (XRD), X-ray absorption fine structure (XAF), and X-ray photoelectron spectroscopy (XPS). As a result, the addition of a small amount of TEOS leaded to the improvement of the thermal stability for TiO2-derived titanate nanotubes. XPS results revealed that Si was combined onto the surface of TiO2-derived titanate nanotubes, forming partial Si-O-Ti chemical bonds. Therefore, it was inferred that the thermal stability could be modified by forming partial Si-O-Ti chemical bonds at interface of silica and TiO2-derived titanate nanotubes. (author)