B-doped TiO2 nanotubes and its photocatalytic activity

Two-step hydrothermal method was developed to prepare B-doped TiO₂ nanotubes (BTNTs). BTNTs was characterized by TEM, XRD, XPS, FT-IR, UV-Vis spectroscopy, its photocatalytic activity was evaluated by the degradation of methyl orange (MO) aqueous solution both under UV light and visible light irritation. The results from TEM indicated that BTNTs with diameter of 10-20 nm and length of several mum was successfully prepared by two-step hydrothermal reaction. The XRD revealed that the BTNTs had crystalline structure of anatase. Especially, the photocatalytic tests indicated that the BTNTs showed higher photocatalytic activity, the degradation of MO were 99.8% and 90.6% under UV light irritation for 90 min and sunlight (55 klux) irritation for 100 min, respectively. FT-IR and XPS results showed that doped boron was present as the form of B³⁺ in BTNTS forming a possible chemical environment like Ti-O-B. Boron atoms can substitute oxygen atoms in the TiO₂ lattice, which causes the band gap narrowing and extend its light absorption into the visible region. Moreover, large specific surface area and one-dimensional structure of BTNTs may be contributed to the greater absorption to organic pollutants and lower combination of electron hole pairs. The synergetic effect of B-doped and one-dimensional tubular structure leads to a higher photoactivity of BTNTs. Additionally, the BTNTs could be easily separated from the reaction solution by sedimentation. These results show that BTNTs will provide possibility to future industrial applications in environmental pollutants cleaning up.