Photodegradation of rhodamine B and methyl orange over one-dimensional TiO2 catalysts under simulated solar irradiation

In this paper, two one-dimensional (1D) TiO2 nanostructures, nanotube and nanowire were synthesized by a hydrothermal method using Degussa P25 TiO2 as a precursor. The synthesized anatase TiO2 nanotubes with the diameters of 10–20 nm and length of several hundred nanometers were formed from P25 and NaOH with the hydrothermal treatment temperature at 150 °C, and anatase TiO2 nanowires with the diameters of 10–40 nm and length up to several micrometers were prepared at 180 °C. The photocatalytic activity of the two nanostructures was evaluated by degrading rhodamine B (RhB) and methyl orange (MO) in aqueous solutions under simulated solar light irradiation. The results suggested that the TiO2 nanocatalysts displayed higher degradation activity compared to P25. For RhB, 98.9% and 91.9% of RhB were removed by nanotubes and nanowires, respectively after 60 min irradiation in comparison to the 81.8% removal by P25. Similar trend was observed for MO, with the removal percentage of 95.6%, 88.3% and 74.9%, respectively by TiO2 nanotubes, nanowires and P25. Meanwhile, RhB and MO showed different photodegradation rates in nanotubes and nanowires suspensions, probably due to the morphology and crystal structure of the TiO2 nanocatalysts which play important roles in the degradation activity of the catalysts.