Effects of sintering temperature on physicochemical properties and photocatalytic activity of titanate nanotubes modified with sulfuric acid

Titanate nanotubes were prepared by using a hydrothermal treatment of TiO2 (Degussa P25) with NaOH aqueous solutions. The as-prepared titanate nanotubes were treated with H2SO4, subsequently sintered at different temperatures. The results of physicochemical characterization and photoactivity analysis revealed that the sintering temperature remarkably altered the phase composition, specific surface area, microstructure, sulfate species as well as photocatalytic activity of the titanate nanotubes modified with sulfuric acid. The sample sintered at 500 °C exhibited much higher activity and better stability than P25, this can be attributed to the suitable crystallization, the porous structure and the abundant surface hydroxyl groups as well as the active sulfate species. As the sintering temperature increased to 600 °C or above, the sulfate species in the samples decomposed, TiO2 particles grew and pore structure shrank, resulting in the poor activities of the samples.