Thermal Stability on Morphology and Crystal Structures of Hydrothermally Synthesized Titanate Nanotubes and Their Photocatalytic Activity

Abstract

Thermal stability on morphology and crystal structure of hydrothermally synthesized titanates nanotubes was investigated. Morphology study by FESEM and TEM revealed that the synthesized titanate nanotubes retained up to 500 °C before converted into nanowires and nanorods at 600 and 700 °C, respectively. The crystal structure of sodium trititanate nanotubes remained unchanged upon thermal treatment from 300 to 500 °C. However at 600 and 700 °C, the interlayer titanate in sodium trititanate samples undergo dimerization like process leading to the formation of an intermediate nanostructured hexatitanate, just before transformed into the corresponding anatase TiO2 crystals. Titanate nanotubes either trititanate or hexatitanate show low photocatalytic activity for methyl orange degradation due to their inter-layered crystal structure.